REVIEW URRENT C OPINION
What are the implications of human papillomavirus status in oropharyngeal tumors for clinical practice? Jan Klozar a and Ruth Tachezy b
Purpose of review Human papillomavirus (HPV) status itself is an important and very probably the strongest prognostic factor in head and neck cancer. Because of the prognostic advantage of patients with HPV-positive cancers, the issue of the quality of life of survivors has become increasingly important. The possibility of treatment deescalation in patients with virally induced tumors is being considered. Many challenges have to be addressed in order to integrate HPV status in the routine decision-making in patients with oropharyngeal cancer. The present review discusses the standardization of detection methods suitable for clinical use and the differences in predictive parameters between patients with HPV-positive and HPV-negative tumors. Recent findings The gold standard for the identification of patients with oropharyngeal tumors etiologically linked to HPV infection is undoubtedly the detection of HPV 16 E6/E7 mRNA. The detection of a surrogate marker of active viral infection, p16ink4a, has a low sensitivity when used alone and must therefore be combined with the detection of HPV DNA or HPV-specific antibodies. The detailed knowledge of the importance of specific prognostic parameters is crucial in the choice of treatment. Nodal staging is probably much less important in HPV-positive cancers. Summary It is of great importance to implement standardized testing for the identification of patients with HPVinduced oropharyngeal tumors. The treatment decision models in HPV-positive tumors have to take into account the probably different prognostic value of nodal parameters. Before introducing treatment deescalation in patients with virally induced tumors into clinical practice, more research and clinical studies are needed. Keywords human papillomavirus, oropharyngeal cancer, prognosis, survival
INTRODUCTION The incidence of head and neck cancer (HNC) is generally stable or decreasing, most significantly in countries with successful tobacco control programs. On the contrary, the incidence of oropharyngeal and particularly tonsillar cancer is steadily on the rise [1,2]. At the same time, the proportion of high-risk human papillomavirus (HPV) presence in oropharyngeal tumors becomes larger which is probably in relation to the increasing prevalence of HPV infection in the population [2–4]. A significant increase over time has been noted, particularly in Europe and North America. The overall prevalence of HPV infection in oropharyngeal cancer is 48%, according to a recent meta-analysis [5 ]. Many articles in the last 15 years have shown that HPV-positive cancer is a distinct molecular and &&
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clinical entity with possible therapeutic implications. Patients with HPV-positive tumors have been reported to have a different risk factor profile, with tobacco and alcohol consumption not playing such an important role as in patients with HPV-negative tumors [6–9].
a Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Medicine, Charles University in Prague, Motol University Hospital and bDepartment of Experimental Virology, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
Correspondence to Professor Jan Klozar, MD, Motol University Hospital, V uvalu 84, 15006 Prague, Czech Republic. Tel: +420 224434303; fax: +420 224434319; e-mail: [email protected] Curr Opin Otolaryngol Head Neck Surg 2014, 22:90–94 DOI:10.1097/MOO.0000000000000030 Volume 22 Number 2 April 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
HPV status in oropharyngeal tumors Klozar and Tachezy
KEY POINTS HPV status itself is an important and very probably the strongest prognostic factor in HNC. The prognostic advantage of HNC patients is strictly linked to patients with tumors with transcriptionally active virus. Not a single test for the detection of virally induced tumors has a sufficient clinical sensitivity and specificity. Traditional clinical prognostic markers seem to be different in patients with HPV-associated tumors. Before introducing de-escalation of the treatment in patients with virally induced tumors into clinical practice more research and clinical studies are needed.
Nowadays, it is accepted that HPV status itself is an important and very probably the strongest prognostic factor in HNC [7,9–12]. From the clinical point of view, a better survival is the most important outcome in patients with HPV-positive tumors. Because of the prognostic advantage of these patients, the issue of the quality of life of survivors has become increasingly relevant. Therefore, the possibility of treatment de-escalation in patients with virally induced tumors is being discussed recently [4]. However, no clinical recommendation exists so far concerning the different treatment options for HPV-positive and HPV-negative cases. As HPV-positive patients seem to have better outcomes regardless of the therapeutic method used [12], new treatment strategies should focus on the reduction of treatment-related toxicity. They can comprise less aggressive surgical options, dose reduction in radiotherapy, avoidance of chemotherapy, and in the future, also newly developed HPV-specific therapies. In summary, it is highly probable that HPV status will, in the near future, play an important role in the choice of treatment intensity and possibly also treatment modality. Several challenges are to be addressed in order to integrate HPV status in the routine decision-making for patients with oropharyngeal cancer. One of them is the standardization of detection methods suitable for clinical use. Testing for HPV and/or its surrogate markers has become quite common in clinical settings in recent years. However, until today, there are no recommendations for the standard procedures for HPV detection in these patients. This can add bias to comparisons of studies involving different groups of patients with oropharyngeal cancer. Also, the reported variation in HPV prevalence in oropharyngeal tumors between diverse parts of the world can be partially
due to the differences in the performance characteristics of detection methods. With the growing importance of HPV status and its future implications for the choice of treatment strategy, it seems appropriate to look for a consensus regarding the markers suitable for use in clinical practice. Such markers should be of high clinical sensitivity and specificity, robust and inexpensive. Another essential factor entering into the clinical decision-making process is the importance of prognostic factors that have been suggested to be different in patients with HPV-positive and HPV-negative tumors. The clinical decision-making should definitely be risk driven and an understanding of all the prognostic variables that predict disease outcome is crucial. Histopathological parameters provide more accurate information and, in regard to prognostic parameters, pathological staging is superior to clinical staging. The treatment of a big part of oropharyngeal cancers is nonsurgical and the knowledge of pathological predictors in these cases is subsequently limited. Surgical treatment of oropharyngeal tumors has recently been considered more often owing to the development of less invasive surgical procedures [13]. Histopathological and molecular examination of surgical specimen of primary tumor and of neck nodes in these cases can lead to more accurate indication and dosage of adjuvant treatments. Some of the traditional prognostic factors suggesting the administration of adjuvant therapy or its intensification in tobacco driven cancers need to be reconsidered in HPV-related cancers. The knowledge of the exact significance of the different predictive parameters in HPV-positive cancers should help tailor the treatment to individual needs in order to provide an optimum oncologic control with minimum morbidity.
DETECTION OF VIRALLY INDUCED TUMORS Unlike in cervical cancer, there are no specific screening programs for the detection of precancerous lesions in HNC and relatively little is known about the natural history of HPV in the oral cavity and oropharynx. Furthermore, oropharyngeal tumors do not usually develop from a clinically detectable precancerous lesion and oral precancerous lesions are mostly linked to tobacco, betel or other carcinogenic substances. It is unlikely that HPV detection could soon play a role in early detection of oral/oropharyngeal cancer or its recurrence [14 ]. Surprisingly, just recently, it has been shown that antibodies specific for HPV oncogenes can be detected years prior to HNC diagnosis.
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However, this finding needs confirmation in larger studies [15 ]. Because of the reasons mentioned in the introduction, HPV testing in HNC becomes an extremely important issue of increasing clinical relevance. Direct methods with amplification of the genome as well as the nonamplification methods were used in studies for the detection of HPV infection in the tissues of HNC patients. They have shown higher prevalence of HPV DNA in oropharyngeal tumors in comparison to healthy controls and have been validated regarding their prognostic significance [16 ]. However, recent studies have found that the prognostic advantage of HNC patients is strictly linked to tumors with transcriptionally active virus [17 ,18,19], which is not contained in all HPV DNA-positive cancers. To assess the presence of active viral infection in patients with head and neck tumors, a variety of viral and surrogate markers have been studied. The detection of HPV mRNA is considered a gold standard but this method needs a good quality sample that allows for the extraction of an intact mRNA – a prerequisite that might be difficult to achieve in clinical practice. Therefore, overexpression of the cyclin-dependent kinase inhibitor, p16ink4a, a surrogate marker for the transforming activity of high-risk HPVs, has been used. The detection of overexpression of p16ink4a protein is a very important tool now commonly used in the clinical setting for improving the diagnostic accuracy, reliability and quality in the histopathology of cervical lesions [20]. Smeets et al. [18] have reported high sensitivity and feasibility for PCR detection of HPV DNA in tumor tissue followed by p16 immunostaining on formalin-fixed, paraffinembedded tumor specimens. The authors have suggested an algorithm for the identification of patients with HPV-related HNC, based primarily on the detection of a diffuse and strong expression of p16ink4a. Others have recommended sequential or combined testing with p16 immunohistochemistry and HPV in-situ hybridization (ISH) as a very specific and sensitive approach. However, their results were obtained using a noncommercial ISH test that might be difficult to establish in a routine setting and the performance characteristics of commercially available tests for ISH are poor [16 ]. Furthermore, we and others have shown that the p16 marker correctly detects the active viral infection in most, but not all tonsillar cancers and in some HNC of other than tonsillar location, p16ink4a is not overexpressed despite the presence of an active HPV infection [7,18,21 ]. Based on a larger series of patients with oropharyngeal tumors, it has been reported that HPV-negative, p16-positive &&
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patients, in regard to their survival, behave as HPV DNA negative and the patient characteristics of this ‘discordant group’ resemble those of HPV-negative patients [17 ,22 ]. All these results emphasize the necessity of using the HPV DNA detection test together with the detection of p16 overexpression for the exact specification of the patients with tumors of viral origin. Noninvasive or less invasive sampling procedures to identify patients with HPV-positive tumors were evaluated in several studies [8,23–26]. It has been demonstrated that the presence of HPV DNA in oral rinses or saliva as well as the detection of HPV-specific antibodies in the sera show good correlation with the presence of HPV DNA in the tumor tissue and appear to be independent favorable prognostic factors [8,14 ,27]. The sensitivity and specificity of the HPV DNA presence in oral rinses as compared with HPV DNA presence in tumor tissue were evaluated in our study and reached 76 and 86%, respectively. The performance of this marker can be increased by combination with the detection of HPV-specific antibodies. These antibodies specific against viral oncoproteins E6/E7 are almost exclusively detected in patients with invasive cancers causally linked to HPV infection. In our study, the detection of HPV-specific antibodies to HPV16 E6/E7 viral oncoproteins showed a sensitivity and specificity of 89 and 96%, respectively, when compared with HPV16 mRNA E6 detection [7]. However, as these data come from a small series, larger studies are needed to confirm this observation. Based on recently published data from a nested study, a combination of the detection of HPV-specific E6/E7 antibodies and overexpression of p16ink4a has been suggested for the identification of patients with oropharyngeal tumors of HPV origin [28]. &&
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PROGNOSTIC MARKERS IN HUMAN PAPILLOMAVIRUS-POSITIVE CANCERS Traditionally, the N classification is considered the most important prognostic factor. It is widely accepted that the presence of positive nodes reduces the probability of survival to about 50% [29]. The N classification does not express all potential prognosticators. In cases where surgery is the first treatment modality, we can get more accurate N staging and additional parameters that are typically used in deciding on adjuvant therapy. Other pathologic nodal features like the number of positive nodes, location of positive nodes and particularly extra capsular spread (ECS) are considered to be good prognosticators. However, it is uncertain whether this is also valid in patients Volume 22 Number 2 April 2014
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HPV status in oropharyngeal tumors Klozar and Tachezy
with HPV-positive tumors and some recent data have suggested that it may not be the case. Several studies have pointed out that the important prognostic value of HPV status outweighs other clinical factors in cohorts with a high proportion of patients with HPV-positive tumors [9,11,30]. Ang et al. [31] have performed a subgroup analysis of patients enrolled in a Radiation Therapy Oncology Group trial, comparing chemoradiation using different radiotherapy regimens. The study recruited 743 patients of whom 433 had oropharyngeal cancer. In a subgroup of 323 oropharyngeal cancer patients, the HPV presence and p16 positivity were assessed. The authors have stated that HPV status was the most important factor both for overall and diseasefree survival. They identified the most influential prognostic factors and based on the results, they divided the cohort according to HPV status, smoking, tumor and nodal stage into three risk groups. In their analysis, N2b and N3 stages had a predictive significance also in patients with p16-positive tumors who were smokers with more than 10 pack-years. However, recently the prognostic value of the N classification and other nodal characteristics has been questioned in patients with HPV-positive tumors. Several studies have not found a prognostic role of nodal parameters. Straetmans et al. [30] have not seen correlation of nodal involvement with survival in their group of tonsillar cancer patients. The presence of nodal involvement seemed to be related to better survival in the group of HPV-positive tumors in their study, whereas it was the opposite in the group of HPV-negative tumors. However, none of these differences was statistically significant. We have recently evaluated the prognostic value of clinical parameters separately in HPV-positive and HPV-negative patients with oral and oropharyngeal tumors. In the HPV-negative group, the univariate analysis revealed pT, pN, number of positive nodes and ECS as significant prognosticators. After adjustment for age, sex, smoking, alcohol consumption and location of tumor, ECS lost its significance and alcohol consumption emerged as a prognostic factor. Smoking did not influence prognosis in the cohort of HPV-negative patients, probably because nearly all patients were smokers. Contrary to the result of the HPV-negative group, none of the prognostic factors studied was significant in patients with HPV-positive tumors. Patients with well differentiated tumors showed a trend for worse diseasespecific survival (DSS) and those with smaller tumors had slightly better DSS, but these differences were not statistically significant [32 ]. Another negative prognostic factor commonly used to justify intensified adjuvant therapy is ECS. &
&
A recent study of Sinha et al. [33 ] questions the role of ECS as a prognosticator in p16-positive oropharyngeal tumors. The authors have shown that the presence of ECS was not associated with lower disease-free survival. Furthermore, in a matched analysis, they could demonstrate that in p16-positive patients with ECS, adjuvant chemoradiation was not associated with superior survival over radiotherapy alone. The intensification of adjuvant radiotherapy by chemotherapy, which is habitually advocated in the presence of ECS, seems not to improve survival in patients with HPV-positive tumors. All these results suggest that nodal involvement plays a much less important prognostic role in HPV-positive tumors. Its value as a negative marker indicating the necessity of adjuvant treatment or its higher intensity should probably be reconsidered.
CONCLUSION The modification of treatment strategy for HPV-positive tumors is probably about to come in the next years. There are several ongoing studies designed to clarify some of the still unanswered questions regarding the safety of treatment deescalation in HPV-positive tumors. The results of these studies, which were reviewed in a recent article in this journal [4], will surely enlarge our knowledge. However, many questions still remain open. We tried to point out two of them. The importance of standardized testing is obvious. The gold standard for the identification of patients with tumors etiologically linked to HPV infection is undoubtedly the detection of HPV16 E6/E7 mRNA, which is difficult to introduce into a routine clinical setting. The detection of the surrogate marker of active viral infection, p16ink4a, already widely used in clinical practice for cervical lesions, has a low sensitivity when used alone and must therefore be combined with HPV DNA detection or detection of HPV-specific antibodies. The detailed knowledge of the importance of specific prognostic parameters is crucial in the choice of treatment. The extent of nodal involvement is among the most important prognosticators in tobacco-related cancers. The predictive value of nodal parameters is probably different in HPVpositive cancers and the future decision models must take it into consideration. Only the results of ongoing and future studies will allow a modification of the treatment approach according to HPV status. In the meantime, it is particularly important to acquire sufficient evidence by means of well designed trials. Gaining clinical knowledge can lead to a modification of guidelines
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and ultimately to the optimal treatment decision for every individual patient with oropharyngeal cancer. Acknowledgements None. Conflicts of interest Cited studies and this review were supported by Granting Agency, Ministry of Health, Czech Republic with grant number: NT/12483. The authors have no conflicts of interest to declare.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Chaturvedi AK, Engels EA, Anderson WF, et al. Incidence trends for human papillomavirus-related and -unrelated oral squamous cell carcinomas in the United States. J Clin Oncol 2008; 26:612–619. 2. Sturgis EM, Cinciripini PM. Trends in head and neck cancer incidence in relation to smoking prevalence: an emerging epidemic of human papillomavirus-associated cancers? Cancer 2007; 110:1429–1435. 3. Hammarstedt L, Lindquist D, Dahlstrand H, et al. Human papillomavirus as a risk factor for the increase in incidence of tonsillar cancer. Int J Cancer 2006; 119:2620–2623. 4. Mehanna H, Olaleye O, Licitra L. Oropharyngeal cancer: is it time to change management according to human papilloma virus status? Curr Opin Otolaryngol Head Neck Surg 2012; 20:120–124. 5. Mehanna H, Beech T, Nicholson T, et al. Prevalence of human papillomavirus && in oropharyngeal and nonoropharyngeal head and neck cancer: systematic review and meta-analysis of trends by time and region. Head Neck 2013; 35:747–755. Metaanalysis demonstrates the rising trends of HPV-positive oropharyngeal cancer in North America and Europe. 6. Gillison ML, D’Souza G, Westra W, et al. Distinct risk factor profiles for human papillomavirus type 16-positive and human papillomavirus type 16-negative head and neck cancers. J Natl Cancer Inst 2008; 100:407–420. 7. Rotnaglova E, Tachezy R, Salakova M, et al. HPV involvement in tonsillar cancer: prognostic significance and clinically relevant markers. Int J Cancer 2011; 129:101–110. 8. Tachezy R, Klozar J, Rubenstein L, et al. Demographic and risk factors in patients with head and neck tumors. J Med Virol 2009; 81:878–887. 9. Hafkamp HC, Manni JJ, Haesevoets A, et al. Marked differences in survival rate between smokers and nonsmokers with HPV 16-associated tonsillar carcinomas. Int J Cancer 2008; 122:2656–2664. 10. Gillison ML. Human papillomavirus and prognosis of oropharyngeal squamous cell carcinoma: implications for clinical research in head and neck cancers. J Clin Oncol 2006; 24:5623–5625. 11. Klozar J, Kratochvil V, Salakova M, et al. HPV status and regional metastasis in the prognosis of oral and oropharyngeal cancer. Eur Arch Otorhinolaryngol 2008; 265 (Suppl 1):S75–S82. 12. Licitra L, Perrone F, Bossi P, et al. High-risk human papillomavirus affects prognosis in patients with surgically treated oropharyngeal squamous cell carcinoma. J Clin Oncol 2006; 24:5630–5636. 13. Adelstein DJ, Ridge JA, Brizel DM, et al. Transoral resection of pharyngeal cancer: summary of a National Cancer Institute Head and Neck Cancer Steering Committee Clinical Trials Planning Meeting, November 6-7, 2011, Arlington, Virginia. Head Neck 2012; 34:1681–1703. 14. Koslabova E, Hamsikova E, Salakova M, et al. Markers of HPV infection and && survival in patients with head and neck tumors. Int J Cancer 2013; 133:1832–1839. The results of the study suggest that the detection of antibodies specific for the HPV-16 E6 and E7 oncoproteins may serve not only as a marker of HPV etiology, but also as a marker of recurrence and a prognostic indicator in patients with HPV-positive tumors. The presence of HPV in the oral rinse correlated with HPV DNA detected in the tumor tissues but was not marker of a recurrent disease.
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15. Kreimer AR, Johansson M, Waterboer T, et al. Evaluation of human papillomavirus antibodies and risk of subsequent head and neck cancer. J Clin Oncol 2013; 31:2708–2715. In this study, the presence of HPV E6-specific antibodies was detected years before the diagnosis of oropharyngeal cancer. 16. Gillison ML, Alemany L, Snijders PJ, et al. Human papillomavirus and diseases && of the upper airway: head and neck cancer and respiratory papillomatosis. Vaccine 2012; 30 (Suppl 5):F34–F54. This article is a review of scientific-based evidence of HPV in HNC. 17. Rietbergen MM, Brakenhoff RH, Bloemena E, et al. Human papillomavirus && detection and comorbidity: critical issues in selection of patients with oropharyngeal cancer for treatment De-escalation trials. Ann Oncol 2013; 24:2740–2745. Based on the results of this study a prognostic model was developed in which patients were classified into three risk groups according to HPV status, nodal stage and comorbidity. This study also emphasizes the importance of performing an HPV DNA-specific test besides p16 immunostaining. 18. Smeets SJ, Hesselink AT, Speel EJ, et al. A novel algorithm for reliable detection of human papillomavirus in paraffin embedded head and neck cancer specimen. Int J Cancer 2007; 121:2465–2472. 19. Weinberger PM, Yu Z, Haffty BG, et al. Molecular classification identifies a subset of human papillomavirus: associated oropharyngeal cancers with favorable prognosis. J Clin Oncol 2006; 24:736–747. 20. Cuzick J, Bergeron C, von Knebel Doeberitz M, et al. New technologies and procedures for cervical cancer screening. Vaccine 2012; 30 (Suppl 5): F107–F116. 21. Hoffmann M, Tribius S, Quabius ES, et al. HPV DNA, E6I-mRNA && expression and p16INK4A immunohistochemistry in head and neck cancer - how valid is p16INK4A as surrogate marker? Cancer Lett 2012; 323:88–96. This study shows that tonsillar SCC is frequently but not always associated with active HPV infections and it also shows that p16ink4A overexpression is not evident in a subgroup of HNSCC with active HPV infection. 22. Holzinger D, Flechtenmacher C, Henfling N, et al. Identification of & oropharyngeal squamous cell carcinomas with active HPV16 involvement by immunohistochemical analysis of the retinoblastoma protein pathway. Int J Cancer 2013; 133:1389–1399. This study addressed whether the expression profile of the cellular proteins from retinoblastoma pathway can serve as surrogate markers for the selection of oropharyngeal tumors of viral origin singly or in combinations. The results show that in fixed biopsy material, the marker combination high p16INK4a/low pRb is well suited to identify oropharyngeal SCC with biologically active HPV16 infection. 23. Herrero R, Castellsague X, Pawlita M, et al. Human papillomavirus and oral cancer: the International Agency for Research on Cancer multicenter study. J Natl Cancer Inst 2003; 95:1772–1783. 24. Smith EM, Ritchie JM, Pawlita M, et al. Human papillomavirus seropositivity and risks of head and neck cancer. Int J Cancer 2007; 120:825–832. 25. Smith EM, Ritchie JM, Summersgill KF, et al. Human papillomavirus in oral exfoliated cells and risk of head and neck cancer. J Natl Cancer Inst 2004; 96:449–455. 26. Zhao M, Rosenbaum E, Carvalho AL, et al. Feasibility of quantitative PCRbased saliva rinse screening of HPV for head and neck cancer. Int J Cancer 2005; 117:605–610. 27. Rubenstein LM, Smith EM, Pawlita M, et al. Human papillomavirus serologic follow-up response and relationship to survival in head and neck cancer: a case-comparison study. Infect Agent Cancer 2011; 6:9. 28. Anantharaman D, Gheit T, Waterboer T, et al. Human papillomavirus infections and upper aero-digestive tract cancers: the ARCAGE study. J Natl Cancer Inst 2013; 105:536–545. 29. Shah J. Head and Neck Surgery and Oncology. Edinburgh: Mosby; 2003. 30. Straetmans JM, Olthof N, Mooren JJ, et al. Human papillomavirus reduces the prognostic value of nodal involvement in tonsillar squamous cell carcinomas. Laryngoscope 2009; 119:1951–1957. 31. Ang KK, Harris J, Wheeler R, et al. Human papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med 2010; 363:24–35. 32. Klozar J, Koslabova E, Kratochvil V, et al. Nodal status is not a prognostic & factor in patients with HPV-positive oral/oropharyngeal tumors. J Surg Oncol 2013; 107:625–633. The study demonstrates the differences in prognostic parameters between HPV positive and negative cancers. 33. Sinha P, Lewis JS Jr, Piccirillo JF, et al. Extracapsular spread and adjuvant & therapy in human papillomavirus-related, p16-positive oropharyngeal carcinoma. Cancer 2012; 118:3519–3530. One of the first studies questioning the prognostic importance of ECS in HPV positive cancers. &&
Volume 22 Number 2 April 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
What are the implications of human papillomavirus status in oropharyngeal tumors for clinical practice? Jan Klozar a and Ruth Tachezy b
Purpose of review Human papillomavirus (HPV) status itself is an important and very probably the strongest prognostic factor in head and neck cancer. Because of the prognostic advantage of patients with HPV-positive cancers, the issue of the quality of life of survivors has become increasingly important. The possibility of treatment deescalation in patients with virally induced tumors is being considered. Many challenges have to be addressed in order to integrate HPV status in the routine decision-making in patients with oropharyngeal cancer. The present review discusses the standardization of detection methods suitable for clinical use and the differences in predictive parameters between patients with HPV-positive and HPV-negative tumors. Recent findings The gold standard for the identification of patients with oropharyngeal tumors etiologically linked to HPV infection is undoubtedly the detection of HPV 16 E6/E7 mRNA. The detection of a surrogate marker of active viral infection, p16ink4a, has a low sensitivity when used alone and must therefore be combined with the detection of HPV DNA or HPV-specific antibodies. The detailed knowledge of the importance of specific prognostic parameters is crucial in the choice of treatment. Nodal staging is probably much less important in HPV-positive cancers. Summary It is of great importance to implement standardized testing for the identification of patients with HPVinduced oropharyngeal tumors. The treatment decision models in HPV-positive tumors have to take into account the probably different prognostic value of nodal parameters. Before introducing treatment deescalation in patients with virally induced tumors into clinical practice, more research and clinical studies are needed. Keywords human papillomavirus, oropharyngeal cancer, prognosis, survival
INTRODUCTION The incidence of head and neck cancer (HNC) is generally stable or decreasing, most significantly in countries with successful tobacco control programs. On the contrary, the incidence of oropharyngeal and particularly tonsillar cancer is steadily on the rise [1,2]. At the same time, the proportion of high-risk human papillomavirus (HPV) presence in oropharyngeal tumors becomes larger which is probably in relation to the increasing prevalence of HPV infection in the population [2–4]. A significant increase over time has been noted, particularly in Europe and North America. The overall prevalence of HPV infection in oropharyngeal cancer is 48%, according to a recent meta-analysis [5 ]. Many articles in the last 15 years have shown that HPV-positive cancer is a distinct molecular and &&
www.co-otolaryngology.com
clinical entity with possible therapeutic implications. Patients with HPV-positive tumors have been reported to have a different risk factor profile, with tobacco and alcohol consumption not playing such an important role as in patients with HPV-negative tumors [6–9].
a Department of Otorhinolaryngology and Head and Neck Surgery, Faculty of Medicine, Charles University in Prague, Motol University Hospital and bDepartment of Experimental Virology, Institute of Hematology and Blood Transfusion, Prague, Czech Republic
Correspondence to Professor Jan Klozar, MD, Motol University Hospital, V uvalu 84, 15006 Prague, Czech Republic. Tel: +420 224434303; fax: +420 224434319; e-mail: [email protected] Curr Opin Otolaryngol Head Neck Surg 2014, 22:90–94 DOI:10.1097/MOO.0000000000000030 Volume 22 Number 2 April 2014
Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited.
HPV status in oropharyngeal tumors Klozar and Tachezy
KEY POINTS HPV status itself is an important and very probably the strongest prognostic factor in HNC. The prognostic advantage of HNC patients is strictly linked to patients with tumors with transcriptionally active virus. Not a single test for the detection of virally induced tumors has a sufficient clinical sensitivity and specificity. Traditional clinical prognostic markers seem to be different in patients with HPV-associated tumors. Before introducing de-escalation of the treatment in patients with virally induced tumors into clinical practice more research and clinical studies are needed.
Nowadays, it is accepted that HPV status itself is an important and very probably the strongest prognostic factor in HNC [7,9–12]. From the clinical point of view, a better survival is the most important outcome in patients with HPV-positive tumors. Because of the prognostic advantage of these patients, the issue of the quality of life of survivors has become increasingly relevant. Therefore, the possibility of treatment de-escalation in patients with virally induced tumors is being discussed recently [4]. However, no clinical recommendation exists so far concerning the different treatment options for HPV-positive and HPV-negative cases. As HPV-positive patients seem to have better outcomes regardless of the therapeutic method used [12], new treatment strategies should focus on the reduction of treatment-related toxicity. They can comprise less aggressive surgical options, dose reduction in radiotherapy, avoidance of chemotherapy, and in the future, also newly developed HPV-specific therapies. In summary, it is highly probable that HPV status will, in the near future, play an important role in the choice of treatment intensity and possibly also treatment modality. Several challenges are to be addressed in order to integrate HPV status in the routine decision-making for patients with oropharyngeal cancer. One of them is the standardization of detection methods suitable for clinical use. Testing for HPV and/or its surrogate markers has become quite common in clinical settings in recent years. However, until today, there are no recommendations for the standard procedures for HPV detection in these patients. This can add bias to comparisons of studies involving different groups of patients with oropharyngeal cancer. Also, the reported variation in HPV prevalence in oropharyngeal tumors between diverse parts of the world can be partially
due to the differences in the performance characteristics of detection methods. With the growing importance of HPV status and its future implications for the choice of treatment strategy, it seems appropriate to look for a consensus regarding the markers suitable for use in clinical practice. Such markers should be of high clinical sensitivity and specificity, robust and inexpensive. Another essential factor entering into the clinical decision-making process is the importance of prognostic factors that have been suggested to be different in patients with HPV-positive and HPV-negative tumors. The clinical decision-making should definitely be risk driven and an understanding of all the prognostic variables that predict disease outcome is crucial. Histopathological parameters provide more accurate information and, in regard to prognostic parameters, pathological staging is superior to clinical staging. The treatment of a big part of oropharyngeal cancers is nonsurgical and the knowledge of pathological predictors in these cases is subsequently limited. Surgical treatment of oropharyngeal tumors has recently been considered more often owing to the development of less invasive surgical procedures [13]. Histopathological and molecular examination of surgical specimen of primary tumor and of neck nodes in these cases can lead to more accurate indication and dosage of adjuvant treatments. Some of the traditional prognostic factors suggesting the administration of adjuvant therapy or its intensification in tobacco driven cancers need to be reconsidered in HPV-related cancers. The knowledge of the exact significance of the different predictive parameters in HPV-positive cancers should help tailor the treatment to individual needs in order to provide an optimum oncologic control with minimum morbidity.
DETECTION OF VIRALLY INDUCED TUMORS Unlike in cervical cancer, there are no specific screening programs for the detection of precancerous lesions in HNC and relatively little is known about the natural history of HPV in the oral cavity and oropharynx. Furthermore, oropharyngeal tumors do not usually develop from a clinically detectable precancerous lesion and oral precancerous lesions are mostly linked to tobacco, betel or other carcinogenic substances. It is unlikely that HPV detection could soon play a role in early detection of oral/oropharyngeal cancer or its recurrence [14 ]. Surprisingly, just recently, it has been shown that antibodies specific for HPV oncogenes can be detected years prior to HNC diagnosis.
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However, this finding needs confirmation in larger studies [15 ]. Because of the reasons mentioned in the introduction, HPV testing in HNC becomes an extremely important issue of increasing clinical relevance. Direct methods with amplification of the genome as well as the nonamplification methods were used in studies for the detection of HPV infection in the tissues of HNC patients. They have shown higher prevalence of HPV DNA in oropharyngeal tumors in comparison to healthy controls and have been validated regarding their prognostic significance [16 ]. However, recent studies have found that the prognostic advantage of HNC patients is strictly linked to tumors with transcriptionally active virus [17 ,18,19], which is not contained in all HPV DNA-positive cancers. To assess the presence of active viral infection in patients with head and neck tumors, a variety of viral and surrogate markers have been studied. The detection of HPV mRNA is considered a gold standard but this method needs a good quality sample that allows for the extraction of an intact mRNA – a prerequisite that might be difficult to achieve in clinical practice. Therefore, overexpression of the cyclin-dependent kinase inhibitor, p16ink4a, a surrogate marker for the transforming activity of high-risk HPVs, has been used. The detection of overexpression of p16ink4a protein is a very important tool now commonly used in the clinical setting for improving the diagnostic accuracy, reliability and quality in the histopathology of cervical lesions [20]. Smeets et al. [18] have reported high sensitivity and feasibility for PCR detection of HPV DNA in tumor tissue followed by p16 immunostaining on formalin-fixed, paraffinembedded tumor specimens. The authors have suggested an algorithm for the identification of patients with HPV-related HNC, based primarily on the detection of a diffuse and strong expression of p16ink4a. Others have recommended sequential or combined testing with p16 immunohistochemistry and HPV in-situ hybridization (ISH) as a very specific and sensitive approach. However, their results were obtained using a noncommercial ISH test that might be difficult to establish in a routine setting and the performance characteristics of commercially available tests for ISH are poor [16 ]. Furthermore, we and others have shown that the p16 marker correctly detects the active viral infection in most, but not all tonsillar cancers and in some HNC of other than tonsillar location, p16ink4a is not overexpressed despite the presence of an active HPV infection [7,18,21 ]. Based on a larger series of patients with oropharyngeal tumors, it has been reported that HPV-negative, p16-positive &&
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patients, in regard to their survival, behave as HPV DNA negative and the patient characteristics of this ‘discordant group’ resemble those of HPV-negative patients [17 ,22 ]. All these results emphasize the necessity of using the HPV DNA detection test together with the detection of p16 overexpression for the exact specification of the patients with tumors of viral origin. Noninvasive or less invasive sampling procedures to identify patients with HPV-positive tumors were evaluated in several studies [8,23–26]. It has been demonstrated that the presence of HPV DNA in oral rinses or saliva as well as the detection of HPV-specific antibodies in the sera show good correlation with the presence of HPV DNA in the tumor tissue and appear to be independent favorable prognostic factors [8,14 ,27]. The sensitivity and specificity of the HPV DNA presence in oral rinses as compared with HPV DNA presence in tumor tissue were evaluated in our study and reached 76 and 86%, respectively. The performance of this marker can be increased by combination with the detection of HPV-specific antibodies. These antibodies specific against viral oncoproteins E6/E7 are almost exclusively detected in patients with invasive cancers causally linked to HPV infection. In our study, the detection of HPV-specific antibodies to HPV16 E6/E7 viral oncoproteins showed a sensitivity and specificity of 89 and 96%, respectively, when compared with HPV16 mRNA E6 detection [7]. However, as these data come from a small series, larger studies are needed to confirm this observation. Based on recently published data from a nested study, a combination of the detection of HPV-specific E6/E7 antibodies and overexpression of p16ink4a has been suggested for the identification of patients with oropharyngeal tumors of HPV origin [28]. &&
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PROGNOSTIC MARKERS IN HUMAN PAPILLOMAVIRUS-POSITIVE CANCERS Traditionally, the N classification is considered the most important prognostic factor. It is widely accepted that the presence of positive nodes reduces the probability of survival to about 50% [29]. The N classification does not express all potential prognosticators. In cases where surgery is the first treatment modality, we can get more accurate N staging and additional parameters that are typically used in deciding on adjuvant therapy. Other pathologic nodal features like the number of positive nodes, location of positive nodes and particularly extra capsular spread (ECS) are considered to be good prognosticators. However, it is uncertain whether this is also valid in patients Volume 22 Number 2 April 2014
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HPV status in oropharyngeal tumors Klozar and Tachezy
with HPV-positive tumors and some recent data have suggested that it may not be the case. Several studies have pointed out that the important prognostic value of HPV status outweighs other clinical factors in cohorts with a high proportion of patients with HPV-positive tumors [9,11,30]. Ang et al. [31] have performed a subgroup analysis of patients enrolled in a Radiation Therapy Oncology Group trial, comparing chemoradiation using different radiotherapy regimens. The study recruited 743 patients of whom 433 had oropharyngeal cancer. In a subgroup of 323 oropharyngeal cancer patients, the HPV presence and p16 positivity were assessed. The authors have stated that HPV status was the most important factor both for overall and diseasefree survival. They identified the most influential prognostic factors and based on the results, they divided the cohort according to HPV status, smoking, tumor and nodal stage into three risk groups. In their analysis, N2b and N3 stages had a predictive significance also in patients with p16-positive tumors who were smokers with more than 10 pack-years. However, recently the prognostic value of the N classification and other nodal characteristics has been questioned in patients with HPV-positive tumors. Several studies have not found a prognostic role of nodal parameters. Straetmans et al. [30] have not seen correlation of nodal involvement with survival in their group of tonsillar cancer patients. The presence of nodal involvement seemed to be related to better survival in the group of HPV-positive tumors in their study, whereas it was the opposite in the group of HPV-negative tumors. However, none of these differences was statistically significant. We have recently evaluated the prognostic value of clinical parameters separately in HPV-positive and HPV-negative patients with oral and oropharyngeal tumors. In the HPV-negative group, the univariate analysis revealed pT, pN, number of positive nodes and ECS as significant prognosticators. After adjustment for age, sex, smoking, alcohol consumption and location of tumor, ECS lost its significance and alcohol consumption emerged as a prognostic factor. Smoking did not influence prognosis in the cohort of HPV-negative patients, probably because nearly all patients were smokers. Contrary to the result of the HPV-negative group, none of the prognostic factors studied was significant in patients with HPV-positive tumors. Patients with well differentiated tumors showed a trend for worse diseasespecific survival (DSS) and those with smaller tumors had slightly better DSS, but these differences were not statistically significant [32 ]. Another negative prognostic factor commonly used to justify intensified adjuvant therapy is ECS. &
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A recent study of Sinha et al. [33 ] questions the role of ECS as a prognosticator in p16-positive oropharyngeal tumors. The authors have shown that the presence of ECS was not associated with lower disease-free survival. Furthermore, in a matched analysis, they could demonstrate that in p16-positive patients with ECS, adjuvant chemoradiation was not associated with superior survival over radiotherapy alone. The intensification of adjuvant radiotherapy by chemotherapy, which is habitually advocated in the presence of ECS, seems not to improve survival in patients with HPV-positive tumors. All these results suggest that nodal involvement plays a much less important prognostic role in HPV-positive tumors. Its value as a negative marker indicating the necessity of adjuvant treatment or its higher intensity should probably be reconsidered.
CONCLUSION The modification of treatment strategy for HPV-positive tumors is probably about to come in the next years. There are several ongoing studies designed to clarify some of the still unanswered questions regarding the safety of treatment deescalation in HPV-positive tumors. The results of these studies, which were reviewed in a recent article in this journal [4], will surely enlarge our knowledge. However, many questions still remain open. We tried to point out two of them. The importance of standardized testing is obvious. The gold standard for the identification of patients with tumors etiologically linked to HPV infection is undoubtedly the detection of HPV16 E6/E7 mRNA, which is difficult to introduce into a routine clinical setting. The detection of the surrogate marker of active viral infection, p16ink4a, already widely used in clinical practice for cervical lesions, has a low sensitivity when used alone and must therefore be combined with HPV DNA detection or detection of HPV-specific antibodies. The detailed knowledge of the importance of specific prognostic parameters is crucial in the choice of treatment. The extent of nodal involvement is among the most important prognosticators in tobacco-related cancers. The predictive value of nodal parameters is probably different in HPVpositive cancers and the future decision models must take it into consideration. Only the results of ongoing and future studies will allow a modification of the treatment approach according to HPV status. In the meantime, it is particularly important to acquire sufficient evidence by means of well designed trials. Gaining clinical knowledge can lead to a modification of guidelines
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and ultimately to the optimal treatment decision for every individual patient with oropharyngeal cancer. Acknowledgements None. Conflicts of interest Cited studies and this review were supported by Granting Agency, Ministry of Health, Czech Republic with grant number: NT/12483. The authors have no conflicts of interest to declare.
REFERENCES AND RECOMMENDED READING Papers of particular interest, published within the annual period of review, have been highlighted as: & of special interest && of outstanding interest 1. Chaturvedi AK, Engels EA, Anderson WF, et al. Incidence trends for human papillomavirus-related and -unrelated oral squamous cell carcinomas in the United States. J Clin Oncol 2008; 26:612–619. 2. Sturgis EM, Cinciripini PM. Trends in head and neck cancer incidence in relation to smoking prevalence: an emerging epidemic of human papillomavirus-associated cancers? Cancer 2007; 110:1429–1435. 3. Hammarstedt L, Lindquist D, Dahlstrand H, et al. Human papillomavirus as a risk factor for the increase in incidence of tonsillar cancer. Int J Cancer 2006; 119:2620–2623. 4. Mehanna H, Olaleye O, Licitra L. Oropharyngeal cancer: is it time to change management according to human papilloma virus status? Curr Opin Otolaryngol Head Neck Surg 2012; 20:120–124. 5. Mehanna H, Beech T, Nicholson T, et al. Prevalence of human papillomavirus && in oropharyngeal and nonoropharyngeal head and neck cancer: systematic review and meta-analysis of trends by time and region. Head Neck 2013; 35:747–755. Metaanalysis demonstrates the rising trends of HPV-positive oropharyngeal cancer in North America and Europe. 6. Gillison ML, D’Souza G, Westra W, et al. Distinct risk factor profiles for human papillomavirus type 16-positive and human papillomavirus type 16-negative head and neck cancers. J Natl Cancer Inst 2008; 100:407–420. 7. Rotnaglova E, Tachezy R, Salakova M, et al. HPV involvement in tonsillar cancer: prognostic significance and clinically relevant markers. Int J Cancer 2011; 129:101–110. 8. Tachezy R, Klozar J, Rubenstein L, et al. Demographic and risk factors in patients with head and neck tumors. J Med Virol 2009; 81:878–887. 9. Hafkamp HC, Manni JJ, Haesevoets A, et al. Marked differences in survival rate between smokers and nonsmokers with HPV 16-associated tonsillar carcinomas. Int J Cancer 2008; 122:2656–2664. 10. Gillison ML. Human papillomavirus and prognosis of oropharyngeal squamous cell carcinoma: implications for clinical research in head and neck cancers. J Clin Oncol 2006; 24:5623–5625. 11. Klozar J, Kratochvil V, Salakova M, et al. HPV status and regional metastasis in the prognosis of oral and oropharyngeal cancer. Eur Arch Otorhinolaryngol 2008; 265 (Suppl 1):S75–S82. 12. Licitra L, Perrone F, Bossi P, et al. High-risk human papillomavirus affects prognosis in patients with surgically treated oropharyngeal squamous cell carcinoma. J Clin Oncol 2006; 24:5630–5636. 13. Adelstein DJ, Ridge JA, Brizel DM, et al. Transoral resection of pharyngeal cancer: summary of a National Cancer Institute Head and Neck Cancer Steering Committee Clinical Trials Planning Meeting, November 6-7, 2011, Arlington, Virginia. Head Neck 2012; 34:1681–1703. 14. Koslabova E, Hamsikova E, Salakova M, et al. Markers of HPV infection and && survival in patients with head and neck tumors. Int J Cancer 2013; 133:1832–1839. The results of the study suggest that the detection of antibodies specific for the HPV-16 E6 and E7 oncoproteins may serve not only as a marker of HPV etiology, but also as a marker of recurrence and a prognostic indicator in patients with HPV-positive tumors. The presence of HPV in the oral rinse correlated with HPV DNA detected in the tumor tissues but was not marker of a recurrent disease.
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15. Kreimer AR, Johansson M, Waterboer T, et al. Evaluation of human papillomavirus antibodies and risk of subsequent head and neck cancer. J Clin Oncol 2013; 31:2708–2715. In this study, the presence of HPV E6-specific antibodies was detected years before the diagnosis of oropharyngeal cancer. 16. Gillison ML, Alemany L, Snijders PJ, et al. Human papillomavirus and diseases && of the upper airway: head and neck cancer and respiratory papillomatosis. Vaccine 2012; 30 (Suppl 5):F34–F54. This article is a review of scientific-based evidence of HPV in HNC. 17. Rietbergen MM, Brakenhoff RH, Bloemena E, et al. Human papillomavirus && detection and comorbidity: critical issues in selection of patients with oropharyngeal cancer for treatment De-escalation trials. Ann Oncol 2013; 24:2740–2745. Based on the results of this study a prognostic model was developed in which patients were classified into three risk groups according to HPV status, nodal stage and comorbidity. This study also emphasizes the importance of performing an HPV DNA-specific test besides p16 immunostaining. 18. Smeets SJ, Hesselink AT, Speel EJ, et al. A novel algorithm for reliable detection of human papillomavirus in paraffin embedded head and neck cancer specimen. Int J Cancer 2007; 121:2465–2472. 19. Weinberger PM, Yu Z, Haffty BG, et al. Molecular classification identifies a subset of human papillomavirus: associated oropharyngeal cancers with favorable prognosis. J Clin Oncol 2006; 24:736–747. 20. Cuzick J, Bergeron C, von Knebel Doeberitz M, et al. New technologies and procedures for cervical cancer screening. Vaccine 2012; 30 (Suppl 5): F107–F116. 21. Hoffmann M, Tribius S, Quabius ES, et al. HPV DNA, E6I-mRNA && expression and p16INK4A immunohistochemistry in head and neck cancer - how valid is p16INK4A as surrogate marker? Cancer Lett 2012; 323:88–96. This study shows that tonsillar SCC is frequently but not always associated with active HPV infections and it also shows that p16ink4A overexpression is not evident in a subgroup of HNSCC with active HPV infection. 22. Holzinger D, Flechtenmacher C, Henfling N, et al. Identification of & oropharyngeal squamous cell carcinomas with active HPV16 involvement by immunohistochemical analysis of the retinoblastoma protein pathway. Int J Cancer 2013; 133:1389–1399. This study addressed whether the expression profile of the cellular proteins from retinoblastoma pathway can serve as surrogate markers for the selection of oropharyngeal tumors of viral origin singly or in combinations. The results show that in fixed biopsy material, the marker combination high p16INK4a/low pRb is well suited to identify oropharyngeal SCC with biologically active HPV16 infection. 23. Herrero R, Castellsague X, Pawlita M, et al. Human papillomavirus and oral cancer: the International Agency for Research on Cancer multicenter study. J Natl Cancer Inst 2003; 95:1772–1783. 24. Smith EM, Ritchie JM, Pawlita M, et al. Human papillomavirus seropositivity and risks of head and neck cancer. Int J Cancer 2007; 120:825–832. 25. Smith EM, Ritchie JM, Summersgill KF, et al. Human papillomavirus in oral exfoliated cells and risk of head and neck cancer. J Natl Cancer Inst 2004; 96:449–455. 26. Zhao M, Rosenbaum E, Carvalho AL, et al. Feasibility of quantitative PCRbased saliva rinse screening of HPV for head and neck cancer. Int J Cancer 2005; 117:605–610. 27. Rubenstein LM, Smith EM, Pawlita M, et al. Human papillomavirus serologic follow-up response and relationship to survival in head and neck cancer: a case-comparison study. Infect Agent Cancer 2011; 6:9. 28. Anantharaman D, Gheit T, Waterboer T, et al. Human papillomavirus infections and upper aero-digestive tract cancers: the ARCAGE study. J Natl Cancer Inst 2013; 105:536–545. 29. Shah J. Head and Neck Surgery and Oncology. Edinburgh: Mosby; 2003. 30. Straetmans JM, Olthof N, Mooren JJ, et al. Human papillomavirus reduces the prognostic value of nodal involvement in tonsillar squamous cell carcinomas. Laryngoscope 2009; 119:1951–1957. 31. Ang KK, Harris J, Wheeler R, et al. Human papillomavirus and survival of patients with oropharyngeal cancer. N Engl J Med 2010; 363:24–35. 32. Klozar J, Koslabova E, Kratochvil V, et al. Nodal status is not a prognostic & factor in patients with HPV-positive oral/oropharyngeal tumors. J Surg Oncol 2013; 107:625–633. The study demonstrates the differences in prognostic parameters between HPV positive and negative cancers. 33. Sinha P, Lewis JS Jr, Piccirillo JF, et al. Extracapsular spread and adjuvant & therapy in human papillomavirus-related, p16-positive oropharyngeal carcinoma. Cancer 2012; 118:3519–3530. One of the first studies questioning the prognostic importance of ECS in HPV positive cancers. &&
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