Author's Accepted Manuscript
Human Papillomavirus-Related Head and Neck Squamous Cell Carcinoma Variants Samir K. El-Mofty DMD, PhD
www.elsevier.com/locate/serndb
PII: DOI: Reference:
S0740-2570(15)00023-4 http://dx.doi.org/10.1053/j.semdp.2015.02.022 YSDIA50408
To appear in: Seminars in Diagnostic Pathology
Cite this article as: Samir K. El-Mofty DMD, PhD, Human PapillomavirusRelated Head and Neck Squamous Cell Carcinoma Variants, Seminars in Diagnostic Pathology, http://dx.doi.org/10.1053/j.semdp.2015.02.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
WENIGVARIANTS Human Papillomavirus‐Related Head and Neck Squamous Cell Carcinoma Variants
Samir K El‐Mofty DMD, PhD. Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8118. St Louis MO. 63110 e‐mail: [email protected] Tel: 314‐362‐2681 Fax: 314‐747‐2040
1
Abstract During the last few decades a phenotypically distinct type of head and neck squamous cell carcinoma (SCC), that is etiologically related to human papillomavirus(HPV), has emerged and its prevalence continues to increase. The tumors are site‐specific with special predilection for the oropharynx. They are morphologically and molecularly distinct and are responsive to different types of treatment modalities, with excellent clinical outcome, in spite of early lymph node metastasis. Microscopically, the carcinomas are nonkeratinizing SCCs. More recently, other variants that are believed to be etiologically related to HPV are reported. As a result, several clinical and pathologic questions have emerged. Importantly, whether the virus is biologically active in these tumors and involved in their pathogenesis, and second, what are the clinical implications with regard to patient management and outcome in these HPV‐related variants. This review is an attempt to answer some of these questions based on information derived from available yet limited number of publications. The variants to be discussed include; nonkeratinizing SCC (NKSCC), NKSCC with maturation (hybrid type), keratinizing SCC (KSSC), basaloid squamous carcinoma (BSCC), undifferentiated carcinoma (UC), papillary SCC (PSCC), small cell carcinoma, adenosquamous carcinoma (AdSCC) and spindle cell (sarcomatoid) carcinoma.
2
Introduction The great majority of head and neck squamous cell carcinomas are microscopically described as kerartinizing squamous cell carcinoma (KSCC). They bear certain resemblance to keratinizing stratified squamous epithelium. Tobacco habits and excessive consumption of alcoholic beverages have been considered to be the main etiologic agents in these carcinomas. The tumors occurred in older patients more commonly affected the oral tongue, floor of the mouth and larynx. Within the last 30 years however, the advent and expanding prevalence of human papillomavirus (HPV)‐related head and neck squamous cell carcinomas, particularly in the oropharynx (OP), was associated with the recognition of a significant change in the established SCC phenotype. The majority of HPV‐relate carcinomas of the OP are nonkeratinizing SCC (NKSCC). These tumors are found to be more responsive to treatment with a favorable patient outcome as compared to HPV negative KSCC. Consequently, alterations in treatment protocols aimed at de‐escalation are currently being evaluated. More recently, other morphologic variants that are HPV positive are reported with increasing frequency in the OP and other head and neck sites. As a result, several clinical and pathologic questions have emerged. Importantly, whether the virus is biologically active in these tumors and involved in their pathogenesis, and second, what are the clinical implications with regard to patient management and outcome in the HPV‐related variants. Identification of HPV as a causative agent in these variants and its prognostic significance is therefore, not merely an academic interest but rather can be of clinical importance in the determination of the patients' outcome and in selection of the proper treatment modalities. Studies on prognostic significance of HPV positive SCC variants in the head and neck are few, and the number of cases studied is limited. Some of these studies show evidence to suggest that specific HPV‐ related morphologic variants may have a favorable outcome, similar to that of HPV positive NKSCC, [1‐ 3]. Yet, other studies suggest that some variants, such as small cell carcinoma, are associated with rather poor prognosis [4,5]. In this article, several head and neck SCC variants that are believed to be HPV‐ related as well as the evidence for their viral etiology and their clinical significance will be reviewed. These include; NKSCC, NKSCC with maturation (hybrid type), KSCC, basaloid squamous carcinoma (BSCC), undifferentiated carcinoma (UC), papillary SCC (PSCC) small cell carcinoma adenosquamous carcinoma (AdSCC) and spindle cell carcinoma HPV‐Related Nonkeratinizing Squamous Cell Carcinoma These tumors have distinct clinical, microscopic and molecular features. The greatest majority of the carcinomas occur in the OP, particularly the palatine and lingual tonsils. They are characterized by 3
younger age at onset [6], weak or no association with alcohol and tobacco use but strong association with sexual behavior, particularly oral sex [7,8]. Despite a characteristic early lymph node metastasis, HPV‐related oropharyngeal squamous cell carcinomas have significantly better treatment outcome and patient survival [9‐11]. Microscopically, HPV‐related squamous cell carcinoma of the OP are distinguished by a nonkeratinizing morphology [6,10,12,13]. The tumors are characterized by relatively monomorphic, ovoid and spindle‐shaped basaloid cells with indistinct cell border (Fig 1). The nuclei are hyperchromatic with high nuclear‐to‐cytoplasmic ratio. The cells form sheets, nests and cords with sharply defined borders. Excessive mitosis and apoptosis as well as comedo‐type necrosis are observed. These carcinomas also show a distinct immunohistochemical profile, namely, strong and diffuse p16 reactivity, very high Ki‐67 labeling scores (Fig 1) and negative or weak staining with p53. p16 over expression is now considered a surrogate marker for HPV‐related NKSCC of the OP [6,13]. p16 is a cell cycle protein associated with tumor suppression by the retinoblastoma pathway. It inhibits hyperphosphorilation of retinoblastoma protein (pRb) thus preventing its dissociation from the transcription factor E2F and the subsequent progression of the S phase of the cell cycle [14,15]. HPV E7 oncoprotein interacts with pRb active form resulting in its functional inactivation. The paradoxical overexpression of an inhibitory protein in actively replicating neoplastic cells is thought to result from feed‐back control secondary to pRb deregulation [14,15]. Because of the observed disparity in clinical outcome of squamous cell carcinomas consequent to their HPV status, there are ongoing clinical investigations to test the efficacy of altering treatment paradigms in documented HPV‐related tumors. Multi‐institutional clinical trials are underway to determine the feasibility of de‐escalated treatment modalities in these cases. It is therefore of importance that HPV status should be reliably and accurately determined. Detecting p16 overexpression by immunohistochemistry is the most commonly used technique for this purpose. The pattern of p16 staining that correlates with transcriptionally active HPV and better patient outcome is strong and diffuse both nuclear and cytoplasmic in more than 75% of the tumor cells (Fig 1) [16‐19]. However, in rare occasions p16 is not specific. Another common detection method is in situ hybridization (ISH) for HPV DNA. While highly specific it is not very sensitive. On the other hand, PCR analysis for HPV DNA is highly sensitive but not necessarily specific. But merely detecting viral DNA by PCR does not indicate whether the virus is transcriptionally active (driver) or a bystander (passenger). E6/E7 mRNA expression is considered the "gold standard" for identification of clinically significant HPV infection in tumor specimens. Reverse transcriptase polymerase chain reaction (RT‐PCR) and real‐time quantitative RT‐PCR (RT‐qPCR) are the main methods used for detection and quantitation of E6/E7 mRNA [20, 21]. More recently, an in situ hybridization method has been developed for detection of transcriptionally‐active HPV in head and neck squamous cell carcinomas (Fig 1). ISH for E6/E7 mRNA is a slide‐based chromogenic assay that has been developed under the name RNA scope (Advanced cell diagnostics, Inc., Hayward, CA) [22,23]. Results from HPV E6/E7 mRNA ISH were found to be highly concordant with p16 immunohistochemistry and RT‐qPCR [22,23]. 4
The nonkeratinizing morphology is significantly more likely to be HPV and p16 positive than KSCC, and to have better overall survival (OS) and disease specific survival (DSS) with a p value of
Human Papillomavirus-Related Head and Neck Squamous Cell Carcinoma Variants Samir K. El-Mofty DMD, PhD
www.elsevier.com/locate/serndb
PII: DOI: Reference:
S0740-2570(15)00023-4 http://dx.doi.org/10.1053/j.semdp.2015.02.022 YSDIA50408
To appear in: Seminars in Diagnostic Pathology
Cite this article as: Samir K. El-Mofty DMD, PhD, Human PapillomavirusRelated Head and Neck Squamous Cell Carcinoma Variants, Seminars in Diagnostic Pathology, http://dx.doi.org/10.1053/j.semdp.2015.02.022 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
WENIGVARIANTS Human Papillomavirus‐Related Head and Neck Squamous Cell Carcinoma Variants
Samir K El‐Mofty DMD, PhD. Department of Pathology and Immunology, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8118. St Louis MO. 63110 e‐mail: [email protected] Tel: 314‐362‐2681 Fax: 314‐747‐2040
1
Abstract During the last few decades a phenotypically distinct type of head and neck squamous cell carcinoma (SCC), that is etiologically related to human papillomavirus(HPV), has emerged and its prevalence continues to increase. The tumors are site‐specific with special predilection for the oropharynx. They are morphologically and molecularly distinct and are responsive to different types of treatment modalities, with excellent clinical outcome, in spite of early lymph node metastasis. Microscopically, the carcinomas are nonkeratinizing SCCs. More recently, other variants that are believed to be etiologically related to HPV are reported. As a result, several clinical and pathologic questions have emerged. Importantly, whether the virus is biologically active in these tumors and involved in their pathogenesis, and second, what are the clinical implications with regard to patient management and outcome in these HPV‐related variants. This review is an attempt to answer some of these questions based on information derived from available yet limited number of publications. The variants to be discussed include; nonkeratinizing SCC (NKSCC), NKSCC with maturation (hybrid type), keratinizing SCC (KSSC), basaloid squamous carcinoma (BSCC), undifferentiated carcinoma (UC), papillary SCC (PSCC), small cell carcinoma, adenosquamous carcinoma (AdSCC) and spindle cell (sarcomatoid) carcinoma.
2
Introduction The great majority of head and neck squamous cell carcinomas are microscopically described as kerartinizing squamous cell carcinoma (KSCC). They bear certain resemblance to keratinizing stratified squamous epithelium. Tobacco habits and excessive consumption of alcoholic beverages have been considered to be the main etiologic agents in these carcinomas. The tumors occurred in older patients more commonly affected the oral tongue, floor of the mouth and larynx. Within the last 30 years however, the advent and expanding prevalence of human papillomavirus (HPV)‐related head and neck squamous cell carcinomas, particularly in the oropharynx (OP), was associated with the recognition of a significant change in the established SCC phenotype. The majority of HPV‐relate carcinomas of the OP are nonkeratinizing SCC (NKSCC). These tumors are found to be more responsive to treatment with a favorable patient outcome as compared to HPV negative KSCC. Consequently, alterations in treatment protocols aimed at de‐escalation are currently being evaluated. More recently, other morphologic variants that are HPV positive are reported with increasing frequency in the OP and other head and neck sites. As a result, several clinical and pathologic questions have emerged. Importantly, whether the virus is biologically active in these tumors and involved in their pathogenesis, and second, what are the clinical implications with regard to patient management and outcome in the HPV‐related variants. Identification of HPV as a causative agent in these variants and its prognostic significance is therefore, not merely an academic interest but rather can be of clinical importance in the determination of the patients' outcome and in selection of the proper treatment modalities. Studies on prognostic significance of HPV positive SCC variants in the head and neck are few, and the number of cases studied is limited. Some of these studies show evidence to suggest that specific HPV‐ related morphologic variants may have a favorable outcome, similar to that of HPV positive NKSCC, [1‐ 3]. Yet, other studies suggest that some variants, such as small cell carcinoma, are associated with rather poor prognosis [4,5]. In this article, several head and neck SCC variants that are believed to be HPV‐ related as well as the evidence for their viral etiology and their clinical significance will be reviewed. These include; NKSCC, NKSCC with maturation (hybrid type), KSCC, basaloid squamous carcinoma (BSCC), undifferentiated carcinoma (UC), papillary SCC (PSCC) small cell carcinoma adenosquamous carcinoma (AdSCC) and spindle cell carcinoma HPV‐Related Nonkeratinizing Squamous Cell Carcinoma These tumors have distinct clinical, microscopic and molecular features. The greatest majority of the carcinomas occur in the OP, particularly the palatine and lingual tonsils. They are characterized by 3
younger age at onset [6], weak or no association with alcohol and tobacco use but strong association with sexual behavior, particularly oral sex [7,8]. Despite a characteristic early lymph node metastasis, HPV‐related oropharyngeal squamous cell carcinomas have significantly better treatment outcome and patient survival [9‐11]. Microscopically, HPV‐related squamous cell carcinoma of the OP are distinguished by a nonkeratinizing morphology [6,10,12,13]. The tumors are characterized by relatively monomorphic, ovoid and spindle‐shaped basaloid cells with indistinct cell border (Fig 1). The nuclei are hyperchromatic with high nuclear‐to‐cytoplasmic ratio. The cells form sheets, nests and cords with sharply defined borders. Excessive mitosis and apoptosis as well as comedo‐type necrosis are observed. These carcinomas also show a distinct immunohistochemical profile, namely, strong and diffuse p16 reactivity, very high Ki‐67 labeling scores (Fig 1) and negative or weak staining with p53. p16 over expression is now considered a surrogate marker for HPV‐related NKSCC of the OP [6,13]. p16 is a cell cycle protein associated with tumor suppression by the retinoblastoma pathway. It inhibits hyperphosphorilation of retinoblastoma protein (pRb) thus preventing its dissociation from the transcription factor E2F and the subsequent progression of the S phase of the cell cycle [14,15]. HPV E7 oncoprotein interacts with pRb active form resulting in its functional inactivation. The paradoxical overexpression of an inhibitory protein in actively replicating neoplastic cells is thought to result from feed‐back control secondary to pRb deregulation [14,15]. Because of the observed disparity in clinical outcome of squamous cell carcinomas consequent to their HPV status, there are ongoing clinical investigations to test the efficacy of altering treatment paradigms in documented HPV‐related tumors. Multi‐institutional clinical trials are underway to determine the feasibility of de‐escalated treatment modalities in these cases. It is therefore of importance that HPV status should be reliably and accurately determined. Detecting p16 overexpression by immunohistochemistry is the most commonly used technique for this purpose. The pattern of p16 staining that correlates with transcriptionally active HPV and better patient outcome is strong and diffuse both nuclear and cytoplasmic in more than 75% of the tumor cells (Fig 1) [16‐19]. However, in rare occasions p16 is not specific. Another common detection method is in situ hybridization (ISH) for HPV DNA. While highly specific it is not very sensitive. On the other hand, PCR analysis for HPV DNA is highly sensitive but not necessarily specific. But merely detecting viral DNA by PCR does not indicate whether the virus is transcriptionally active (driver) or a bystander (passenger). E6/E7 mRNA expression is considered the "gold standard" for identification of clinically significant HPV infection in tumor specimens. Reverse transcriptase polymerase chain reaction (RT‐PCR) and real‐time quantitative RT‐PCR (RT‐qPCR) are the main methods used for detection and quantitation of E6/E7 mRNA [20, 21]. More recently, an in situ hybridization method has been developed for detection of transcriptionally‐active HPV in head and neck squamous cell carcinomas (Fig 1). ISH for E6/E7 mRNA is a slide‐based chromogenic assay that has been developed under the name RNA scope (Advanced cell diagnostics, Inc., Hayward, CA) [22,23]. Results from HPV E6/E7 mRNA ISH were found to be highly concordant with p16 immunohistochemistry and RT‐qPCR [22,23]. 4
The nonkeratinizing morphology is significantly more likely to be HPV and p16 positive than KSCC, and to have better overall survival (OS) and disease specific survival (DSS) with a p value of
