The Laryngoscope C 2014 The American Laryngological, V
Rhinological and Otological Society, Inc.
Contemporary Review
PET/CT in Head and Neck Oncology: State-of-the-Art 2013 Jonas T. Johnson, MD; Barton F. Branstetter IV, MD Objectives/Hypothesis: Combined positron emission tomography with simultaneous computed tomography (PET/CT performed using 18F-fluorodeoxyglucose [FDG] as a radiopharmaceutical) results in improvement in anatomic localization of tumor. This review explores the contemporary application of PET/CT to pretreatment assessment, posttreatment monitoring, and subsequent treatment planning for patients with squamous carcinoma of the head and neck. Data Sources: Contemporary publications on the use of PET/CT in head and neck oncology are reviewed and synthesized. Review Method: This review presents selected literature interpreted by expert opinion. Results: PET/CT is highly sensitive in staging of patients with squamous cancer of the head and neck. The sensitivity is limited by tumor size, and PET/CT cannot currently replace the information obtained from elective neck dissection in the assessment of cervical metastases. In the setting of posttreatment monitoring, PET/CT allows for identification of persistent carcinoma prior to clinical observation in approximately two-thirds of cases. However, contemporary reports do not allow assessment of cost effectiveness, and they do not allow determination if the application of PET/CT in this setting results in improved treatment outcomes. PET/CT is insensitive to evaluation of patients with glandular tumors, and those with low volume tumors and cystic metastases. Conclusions: PET/CT requires further evaluation before recommendations can be made regarding comparative effectiveness when compared to CT or MRI for posttreatment monitoring. The improved sensitivity and specificity of PET/CT during treatment planning justifies its use in this setting for patients with advanced stage squamous cancer of the head and neck. Key Words: PET/CT; head and neck oncology. Laryngoscope, 124:913–915, 2014
INTRODUCTION Combined positron emission tomography and computed tomography (PET/CT) is performed in modern clinical practice using (18F)-fluorodeoxyglucose (FDG), a glucose analog, as the radiopharmaceutical. The addition of simultaneous CT adds precise anatomic definition to the physiologic FDG uptake and results in an improvement in anatomic localization.1 PET/CT technology is now widely employed by many leading cancer centers across the country; however, it is essential to note that the National Comprehensive Cancer Network (NCCN) guidelines do not require PET/CT. Similarly, the Radiation Therapy Oncology Group (RTOG) does not include PET/CT in staging guidelines. This review will discuss the use of PET/CT in head and neck oncology. It will compare PET/CT with other modalities and emphasize when PET/CT is not indicated.
From the Departments of Otolaryngology (J.T.J., B.F.B) and Radiology (B.F.B.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A. Editor’s Note: This Manuscript was accepted for publication November 26, 2012. Presented to the Annual Meeting of the Triological Society as the 2012 Joseph Ogura Lecture, San Diego, CA, U.S.A., April 20, 2012. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Jonas T. Johnson, MD, Department of Otolaryngology, UPMC, 200 Lothrop Street, EEI Suite 500, Pittsburgh PA 15213. E-mail: [email protected] DOI: 10.1002/lary.23942
Laryngoscope 124: April 2014
DISCUSSION Purpose of Oncological Imaging PET/CT represents the most sensitive of currently available standardized imaging modalities. PET/CT is employed commonly for tumor staging, as well as for assistance in identification of cancer metastatic to the cervical lymph nodes from a primary that has not been identified. PET/CT can be employed for treatment planning and is widely used for monitoring and surveillance. Lastly, PET/ CT can be employed for restaging of recurrent disease.
Pre-Treatment Staging PET/CT employed routinely in the pretreatment evaluation of patients with advanced head and neck cancer will assist in the identification of distant metastasis as well as second primary cancers. Dietl et al.2 report that previously unrecognized evidence of distant metastasis was identified in 17% of patients, while second primary tumors were identified in 11%. Johansen et al. 3 studied a cohort of 60 new cancer patients. PET/CT identified 18 clinically important, previously unknown tumor deposits. In six patients (10%), either a new primary or distant metastasis was identified. The negative predictive value of PET/CT is nearly 100% for second primaries and metastatic disease; however, PET/CT can be plagued by false positives.4 To date, no good cost-effectiveness data exists regarding the costs related to false positives on PET/CT. Johnson and Branstetter: PET/CT in Head and Neck Oncology
913
Unfortunately, PET/CT lacks sensitivity to detect microscopic metastatic disease. It is estimated that a metastatic deposit must exceed 5 3 5 3 5 mm to assure detection with PET/CT. Accordingly, this modality cannot replace the accuracy of neck dissection in the identification of occult cervical metastasis.5 The bottom line indicates that PET/CT has sensitivity which exceeds that of either CT or MR alone. Findings may influence therapeutic decisions; however, there does not currently exist good cost-effectiveness data. PET/CT remains inadequate to identify small occult metastasis. The best available data on cervical nodes is from histology available after neck dissection. Microscopic distant metastatic disease may be overlooked and will only be evident with the passage of time.
Cancer from an Unknown Primary It is estimated that 2% to 9% of all head and neck cancer patients present with metastatic cancer in the cervical lymphatics from a primary, which is difficult or impossible to find with physical examination, panendoscopy, conventional imaging, and blind biopsies. The precise understanding of this entity of cancer from an unknown primary (CUP) is made difficult because there is no standard convention for the evaluation of these patients. It has been suggested that PET/CT may identify 38% to 87% of primary tumors.6,7 One study undertook flexible fiberoptic examination of the upper aerodigestive tract and PET/CT prior to endoscopic evaluation and biopsy directed to possible primary sites under anesthesia. In this prospective study, the surgeons were blinded to the findings on PET until the endoscopic evaluation under anesthesia was accomplished. The surgeons were able to find 5/20 primaries without PET. When PET was used to supplement the examination, the identification of a second primary improved to 11/20.8 The bottom line indicates that PET/CT helps identify CUP in approximately one-third of cases. At issue, of course, is the threshold of sensitivity of PET. Tumors that are superficial and small will fail to demonstrate the necessary FDG avidity to allow localization with PET/CT.
Surveillance and Monitoring PET/CT is commonly employed to monitor response to therapy. This has proved especially valuable in patients with a high-risk of recurrence.9 PET/CT is superior to CT in distinguished metabolically active tumors from residual anatomic deformity following completion of chemoradiation. In one study involving 112 patients, 50 CT abnormalities were observed following completion of therapy. Forty-one of these abnormalities, ranging in size from 10 mm to 44 mm, underwent observation only based on PET characteristics. None of these patients eventually developed recurrent disease, while the false positive rate with CT alone was 38%. Nine patients who demonstrated FDG-avid persistence, with tumor size 10 mm to 25 mm, underwent surgery. The persistence of viable tumor was confirmed in six patients.10 These data emphasizes the potential for PET/CT to allow the treatment team an opportunity to avoid intervention in Laryngoscope 124: April 2014
914
patients with a complete tumor response who have not normalized their anatomy. At the University of Pittsburgh Medical Center, PET/CT data on over 300 patients treated nonoperatively has been collected prospectively.11 Recurrent disease was eventually observed in approximately one-third of patients. PET/CT provided recognition of recurrent disease on average 6 to 12 months before clinical recognition; however, these data do not allow determination if PET/CT resulted in improved disease-free survival. The bottom line indicates that when used for surveillance after completion of therapy, PET/CT should not be employed sooner than 8 weeks after completion of therapy. PET/CT examination sooner than 8 weeks results in an unacceptable incidence of false positive exams. Positive findings are best confirmed by biopsy before retreatment. The negative predictive value of PET/CT exceeds 95%. When PET/CT demonstrates no FDG avidity or major improvement from baseline, patients can be monitored without intervention and offered reevaluation at 3 month intervals. Patients with negative PET/CT 18 to 24 months after the completion of therapy experience recurrent disease in fewer than 10% of cases; and patients with two consecutive negative scans are 98% likely to be cured.12 The interval at which PET/CT should be repeated in the setting of a negative posttreatment surveillance PET/ CT is not able to be determined based upon the current data. We have observed a rare patient develop what appears to be recurrent disease up to 26 months after completion of treatment with interval negative PET/CT scans. The incidence of this occurrence is clearly less than 10%. In the setting of improvement in PET/CT, we currently use a 3-month interval to repeat PET/CT. This recommendation is based upon our personal bias and is not yet evidenced-based. More data is needed to determine if early recognition of persistent cancer results in improved disease control. Similarly, current data does not allow us to distinguish among squamous cancers that occur at different sites or between HPV1 and HPV2 squamous cell carcinoma. Lastly, the radiation exposure to the neck from PET/CT is trivial when compared to therapeutic irradiation that most patients have already received. In general, the whole body irradiation generated by PET adds negligible risk in this patient population.
When PET/CT Is Not Indicated PET/CT should not be employed in the diagnostic evaluation of a patient until a malignant diagnosis has been made. PET/CT is not indicated for Stage I/II tumors. PET/CT is appropriate for pretreatment staging in all patients with Stage III/IV squamous cell cancer. It should also not be used for glandular tumors that are notoriously nonavid for FDG, for example, thyroid cancer. Differentiated thyroid cancer is characteristically not FDG-avid. PET/CT is used selectively in the evaluation of previously treated differentiated thyroid cancer in the setting of elevated thyroglobulin and a negative radio-iodine scan. Salivary glandular tumors are notoriously difficult to classify with PET/CT. Many malignancies are not evident on PET/CT, whereas many benign lesions have Johnson and Branstetter: PET/CT in Head and Neck Oncology
high FDG avidity. Lesions identified within the parotid gland should not automatically be considered metastatic disease, even with an established diagnosis of malignancy. Also, PET/CT should not be used to monitor patients with salivary malignancies unless the patient’s tumor has been documented as FDG-avid. Whole body PET/CT identifies many thyroid lesions that are incidental to the primary tumor. Diffuse PET uptake within the thyroid gland is considered a benign finding, but a focal mass with elevated FDG uptake is concerning and fine needle aspiration biopsy (FNAB) is warranted. Approximately one-third of focally FDG-avid thyroid lesions are found to be malignant.13
CONCLUSION PET/CT has become a critical tool in oncologic imaging of head and neck cancer. It is useful in staging, planning, monitoring, and restaging. Unfortunately there remain many important issues that require resolution. In general, patients should have the first posttreatment surveillance PET/CT between 8 to 12 weeks after completion of therapy. Following completion of posttherapeutic surveillance PET/CT, a frequently asked question is when will subsequent PET/CT be required. At our institution, we perform PET/CT every 3 months until the examination is judged normal. At that point, repeat surveillance PET/CT can be accomplished at 6 month intervals until 18 to 24 months following completion of therapy. PET/CT at 18 to 24 months judged normal is a reasonable indication to stop routine PET/CT surveillance, and the treatment team can rely on clinical evaluation for subsequent monitoring. The observation that PET/CT allows identification of recurrence disease 6 to 12 months before the recurrences identified on clinical examination suggest that there may be therapeutic advantage. However, to date no good evidence exists that demonstrates improved local regional control or disease-free survival in patients monitored with PET/CT, when compared to other cohorts of patients. Until
Laryngoscope 124: April 2014
these data become clinically available, the routine use of PET/CT for monitoring of head and neck tumors will remain a contentious cost/benefit question.
BIBLIOGRAPHY 1. Branstetter BF, Blodgett TM, Zimmer LA, et al. Head and neck malignancy: is PET/CT more accurate than PET or CT alone? Radiology 2005;235:580–586. 2. Dietl B, Marienhagen J, Kuhnel T, Schreyer A, Kolbl O. The impact of FDG-PET/CT on the management of head and neck tumours: the radiotherapist’s perspective. Oral Oncol 2008;44:504–508. 3. Johansen J, Buus S, Loft A, et al. Prospective study of 18FDG-PET in the detection and management of patients with lymph node metastases to the neck from an unknown primary tumor. Results from the DAHANCA-13 study. Head Neck 2008;30:471–478. 4. O’Neill JP, Moynagh M, Kavanagh E, O’Dwyer T. Prospective, blinded trial of whole-body magnetic resonance imaging versus computed tomography positron emission tomography in staging primary and recurrent cancer of the head and neck. J Laryngol Otol 2010;124:1274– 1277. 5. Agarwal V, Branstetter BF 4th, Johnson JT. Indications for PET/CT in the head and neck. Otolaryngol Clin North Am 2008;41:23–49, v. 6. Yabuki K, Tsukuda M, Horiuchi C, Taguchi T, Nishimura G. Role of 18F-FDG PET in detecting primary site in the patient with primary unknown carcinoma. Eur Arch Otorhinolaryngol 2010;267: 1785–1792. 7. Roh JL, Kim JS, Lee JH, et al. Utility of combined (18)F-fluorodeoxyglucose-positron emission tomography and computed tomography in patients with cervical metastases from unknown primary tumors. Oral Oncol 2009;45:218–224. 8. Rudmik L, Lau HY, Matthews TW, et al. Clinical utility of PET/CT in the evaluation of head and neck squamous cell carcinoma with an unknown primary: a prospective clinical trial. Head Neck 2011;33: 935–940. 9. Moeller BJ, Rana V, Cannon BA, et al. Prospective risk-adjusted [18F]Fluorodeoxyglucose positron emission tomography and computed tomography assessment of radiation response in head and neck cancer. J Clin Oncol 2009;27:2509–2515. 10. Porceddu SV, Pryor DI, Burmeister E, et al. Results of a prospective study of positron emission tomography-directed management of residual nodal abnormalities in node-positive head and neck cancer after definitive radiotherapy with or without systemic therapy. Head Neck 2011;33:1675–1682. 11. Beswick DM, Gooding WE, Johnson JT, Branstetter BF 4th. Temporal patterns of head and neck squamous cell carcinoma recurrence with positron-emission tomography/computed tomography monitoring. Laryngoscope 2012;122:1512–1517. 12. McDermott M, Hughes MA, Rath T, et al. Negative predictive value of surveillance PET/CT in head and neck squamous cell cancer. Am J Neuroradiol 2013;34:1632–1636. 13. Shie P, Cardarelli R, Sprawls K, Fulda KG, Taur A. Systematic review: prevalence of malignant incidental thyroid nodules identified on fluorine-18 fluorodeoxyglucose positron emission tomography. Nucl Med Commun 2009;30:742–748.
Johnson and Branstetter: PET/CT in Head and Neck Oncology
915
Rhinological and Otological Society, Inc.
Contemporary Review
PET/CT in Head and Neck Oncology: State-of-the-Art 2013 Jonas T. Johnson, MD; Barton F. Branstetter IV, MD Objectives/Hypothesis: Combined positron emission tomography with simultaneous computed tomography (PET/CT performed using 18F-fluorodeoxyglucose [FDG] as a radiopharmaceutical) results in improvement in anatomic localization of tumor. This review explores the contemporary application of PET/CT to pretreatment assessment, posttreatment monitoring, and subsequent treatment planning for patients with squamous carcinoma of the head and neck. Data Sources: Contemporary publications on the use of PET/CT in head and neck oncology are reviewed and synthesized. Review Method: This review presents selected literature interpreted by expert opinion. Results: PET/CT is highly sensitive in staging of patients with squamous cancer of the head and neck. The sensitivity is limited by tumor size, and PET/CT cannot currently replace the information obtained from elective neck dissection in the assessment of cervical metastases. In the setting of posttreatment monitoring, PET/CT allows for identification of persistent carcinoma prior to clinical observation in approximately two-thirds of cases. However, contemporary reports do not allow assessment of cost effectiveness, and they do not allow determination if the application of PET/CT in this setting results in improved treatment outcomes. PET/CT is insensitive to evaluation of patients with glandular tumors, and those with low volume tumors and cystic metastases. Conclusions: PET/CT requires further evaluation before recommendations can be made regarding comparative effectiveness when compared to CT or MRI for posttreatment monitoring. The improved sensitivity and specificity of PET/CT during treatment planning justifies its use in this setting for patients with advanced stage squamous cancer of the head and neck. Key Words: PET/CT; head and neck oncology. Laryngoscope, 124:913–915, 2014
INTRODUCTION Combined positron emission tomography and computed tomography (PET/CT) is performed in modern clinical practice using (18F)-fluorodeoxyglucose (FDG), a glucose analog, as the radiopharmaceutical. The addition of simultaneous CT adds precise anatomic definition to the physiologic FDG uptake and results in an improvement in anatomic localization.1 PET/CT technology is now widely employed by many leading cancer centers across the country; however, it is essential to note that the National Comprehensive Cancer Network (NCCN) guidelines do not require PET/CT. Similarly, the Radiation Therapy Oncology Group (RTOG) does not include PET/CT in staging guidelines. This review will discuss the use of PET/CT in head and neck oncology. It will compare PET/CT with other modalities and emphasize when PET/CT is not indicated.
From the Departments of Otolaryngology (J.T.J., B.F.B) and Radiology (B.F.B.), University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, U.S.A. Editor’s Note: This Manuscript was accepted for publication November 26, 2012. Presented to the Annual Meeting of the Triological Society as the 2012 Joseph Ogura Lecture, San Diego, CA, U.S.A., April 20, 2012. The authors have no funding, financial relationships, or conflicts of interest to disclose. Send correspondence to Jonas T. Johnson, MD, Department of Otolaryngology, UPMC, 200 Lothrop Street, EEI Suite 500, Pittsburgh PA 15213. E-mail: [email protected] DOI: 10.1002/lary.23942
Laryngoscope 124: April 2014
DISCUSSION Purpose of Oncological Imaging PET/CT represents the most sensitive of currently available standardized imaging modalities. PET/CT is employed commonly for tumor staging, as well as for assistance in identification of cancer metastatic to the cervical lymph nodes from a primary that has not been identified. PET/CT can be employed for treatment planning and is widely used for monitoring and surveillance. Lastly, PET/ CT can be employed for restaging of recurrent disease.
Pre-Treatment Staging PET/CT employed routinely in the pretreatment evaluation of patients with advanced head and neck cancer will assist in the identification of distant metastasis as well as second primary cancers. Dietl et al.2 report that previously unrecognized evidence of distant metastasis was identified in 17% of patients, while second primary tumors were identified in 11%. Johansen et al. 3 studied a cohort of 60 new cancer patients. PET/CT identified 18 clinically important, previously unknown tumor deposits. In six patients (10%), either a new primary or distant metastasis was identified. The negative predictive value of PET/CT is nearly 100% for second primaries and metastatic disease; however, PET/CT can be plagued by false positives.4 To date, no good cost-effectiveness data exists regarding the costs related to false positives on PET/CT. Johnson and Branstetter: PET/CT in Head and Neck Oncology
913
Unfortunately, PET/CT lacks sensitivity to detect microscopic metastatic disease. It is estimated that a metastatic deposit must exceed 5 3 5 3 5 mm to assure detection with PET/CT. Accordingly, this modality cannot replace the accuracy of neck dissection in the identification of occult cervical metastasis.5 The bottom line indicates that PET/CT has sensitivity which exceeds that of either CT or MR alone. Findings may influence therapeutic decisions; however, there does not currently exist good cost-effectiveness data. PET/CT remains inadequate to identify small occult metastasis. The best available data on cervical nodes is from histology available after neck dissection. Microscopic distant metastatic disease may be overlooked and will only be evident with the passage of time.
Cancer from an Unknown Primary It is estimated that 2% to 9% of all head and neck cancer patients present with metastatic cancer in the cervical lymphatics from a primary, which is difficult or impossible to find with physical examination, panendoscopy, conventional imaging, and blind biopsies. The precise understanding of this entity of cancer from an unknown primary (CUP) is made difficult because there is no standard convention for the evaluation of these patients. It has been suggested that PET/CT may identify 38% to 87% of primary tumors.6,7 One study undertook flexible fiberoptic examination of the upper aerodigestive tract and PET/CT prior to endoscopic evaluation and biopsy directed to possible primary sites under anesthesia. In this prospective study, the surgeons were blinded to the findings on PET until the endoscopic evaluation under anesthesia was accomplished. The surgeons were able to find 5/20 primaries without PET. When PET was used to supplement the examination, the identification of a second primary improved to 11/20.8 The bottom line indicates that PET/CT helps identify CUP in approximately one-third of cases. At issue, of course, is the threshold of sensitivity of PET. Tumors that are superficial and small will fail to demonstrate the necessary FDG avidity to allow localization with PET/CT.
Surveillance and Monitoring PET/CT is commonly employed to monitor response to therapy. This has proved especially valuable in patients with a high-risk of recurrence.9 PET/CT is superior to CT in distinguished metabolically active tumors from residual anatomic deformity following completion of chemoradiation. In one study involving 112 patients, 50 CT abnormalities were observed following completion of therapy. Forty-one of these abnormalities, ranging in size from 10 mm to 44 mm, underwent observation only based on PET characteristics. None of these patients eventually developed recurrent disease, while the false positive rate with CT alone was 38%. Nine patients who demonstrated FDG-avid persistence, with tumor size 10 mm to 25 mm, underwent surgery. The persistence of viable tumor was confirmed in six patients.10 These data emphasizes the potential for PET/CT to allow the treatment team an opportunity to avoid intervention in Laryngoscope 124: April 2014
914
patients with a complete tumor response who have not normalized their anatomy. At the University of Pittsburgh Medical Center, PET/CT data on over 300 patients treated nonoperatively has been collected prospectively.11 Recurrent disease was eventually observed in approximately one-third of patients. PET/CT provided recognition of recurrent disease on average 6 to 12 months before clinical recognition; however, these data do not allow determination if PET/CT resulted in improved disease-free survival. The bottom line indicates that when used for surveillance after completion of therapy, PET/CT should not be employed sooner than 8 weeks after completion of therapy. PET/CT examination sooner than 8 weeks results in an unacceptable incidence of false positive exams. Positive findings are best confirmed by biopsy before retreatment. The negative predictive value of PET/CT exceeds 95%. When PET/CT demonstrates no FDG avidity or major improvement from baseline, patients can be monitored without intervention and offered reevaluation at 3 month intervals. Patients with negative PET/CT 18 to 24 months after the completion of therapy experience recurrent disease in fewer than 10% of cases; and patients with two consecutive negative scans are 98% likely to be cured.12 The interval at which PET/CT should be repeated in the setting of a negative posttreatment surveillance PET/ CT is not able to be determined based upon the current data. We have observed a rare patient develop what appears to be recurrent disease up to 26 months after completion of treatment with interval negative PET/CT scans. The incidence of this occurrence is clearly less than 10%. In the setting of improvement in PET/CT, we currently use a 3-month interval to repeat PET/CT. This recommendation is based upon our personal bias and is not yet evidenced-based. More data is needed to determine if early recognition of persistent cancer results in improved disease control. Similarly, current data does not allow us to distinguish among squamous cancers that occur at different sites or between HPV1 and HPV2 squamous cell carcinoma. Lastly, the radiation exposure to the neck from PET/CT is trivial when compared to therapeutic irradiation that most patients have already received. In general, the whole body irradiation generated by PET adds negligible risk in this patient population.
When PET/CT Is Not Indicated PET/CT should not be employed in the diagnostic evaluation of a patient until a malignant diagnosis has been made. PET/CT is not indicated for Stage I/II tumors. PET/CT is appropriate for pretreatment staging in all patients with Stage III/IV squamous cell cancer. It should also not be used for glandular tumors that are notoriously nonavid for FDG, for example, thyroid cancer. Differentiated thyroid cancer is characteristically not FDG-avid. PET/CT is used selectively in the evaluation of previously treated differentiated thyroid cancer in the setting of elevated thyroglobulin and a negative radio-iodine scan. Salivary glandular tumors are notoriously difficult to classify with PET/CT. Many malignancies are not evident on PET/CT, whereas many benign lesions have Johnson and Branstetter: PET/CT in Head and Neck Oncology
high FDG avidity. Lesions identified within the parotid gland should not automatically be considered metastatic disease, even with an established diagnosis of malignancy. Also, PET/CT should not be used to monitor patients with salivary malignancies unless the patient’s tumor has been documented as FDG-avid. Whole body PET/CT identifies many thyroid lesions that are incidental to the primary tumor. Diffuse PET uptake within the thyroid gland is considered a benign finding, but a focal mass with elevated FDG uptake is concerning and fine needle aspiration biopsy (FNAB) is warranted. Approximately one-third of focally FDG-avid thyroid lesions are found to be malignant.13
CONCLUSION PET/CT has become a critical tool in oncologic imaging of head and neck cancer. It is useful in staging, planning, monitoring, and restaging. Unfortunately there remain many important issues that require resolution. In general, patients should have the first posttreatment surveillance PET/CT between 8 to 12 weeks after completion of therapy. Following completion of posttherapeutic surveillance PET/CT, a frequently asked question is when will subsequent PET/CT be required. At our institution, we perform PET/CT every 3 months until the examination is judged normal. At that point, repeat surveillance PET/CT can be accomplished at 6 month intervals until 18 to 24 months following completion of therapy. PET/CT at 18 to 24 months judged normal is a reasonable indication to stop routine PET/CT surveillance, and the treatment team can rely on clinical evaluation for subsequent monitoring. The observation that PET/CT allows identification of recurrence disease 6 to 12 months before the recurrences identified on clinical examination suggest that there may be therapeutic advantage. However, to date no good evidence exists that demonstrates improved local regional control or disease-free survival in patients monitored with PET/CT, when compared to other cohorts of patients. Until
Laryngoscope 124: April 2014
these data become clinically available, the routine use of PET/CT for monitoring of head and neck tumors will remain a contentious cost/benefit question.
BIBLIOGRAPHY 1. Branstetter BF, Blodgett TM, Zimmer LA, et al. Head and neck malignancy: is PET/CT more accurate than PET or CT alone? Radiology 2005;235:580–586. 2. Dietl B, Marienhagen J, Kuhnel T, Schreyer A, Kolbl O. The impact of FDG-PET/CT on the management of head and neck tumours: the radiotherapist’s perspective. Oral Oncol 2008;44:504–508. 3. Johansen J, Buus S, Loft A, et al. Prospective study of 18FDG-PET in the detection and management of patients with lymph node metastases to the neck from an unknown primary tumor. Results from the DAHANCA-13 study. Head Neck 2008;30:471–478. 4. O’Neill JP, Moynagh M, Kavanagh E, O’Dwyer T. Prospective, blinded trial of whole-body magnetic resonance imaging versus computed tomography positron emission tomography in staging primary and recurrent cancer of the head and neck. J Laryngol Otol 2010;124:1274– 1277. 5. Agarwal V, Branstetter BF 4th, Johnson JT. Indications for PET/CT in the head and neck. Otolaryngol Clin North Am 2008;41:23–49, v. 6. Yabuki K, Tsukuda M, Horiuchi C, Taguchi T, Nishimura G. Role of 18F-FDG PET in detecting primary site in the patient with primary unknown carcinoma. Eur Arch Otorhinolaryngol 2010;267: 1785–1792. 7. Roh JL, Kim JS, Lee JH, et al. Utility of combined (18)F-fluorodeoxyglucose-positron emission tomography and computed tomography in patients with cervical metastases from unknown primary tumors. Oral Oncol 2009;45:218–224. 8. Rudmik L, Lau HY, Matthews TW, et al. Clinical utility of PET/CT in the evaluation of head and neck squamous cell carcinoma with an unknown primary: a prospective clinical trial. Head Neck 2011;33: 935–940. 9. Moeller BJ, Rana V, Cannon BA, et al. Prospective risk-adjusted [18F]Fluorodeoxyglucose positron emission tomography and computed tomography assessment of radiation response in head and neck cancer. J Clin Oncol 2009;27:2509–2515. 10. Porceddu SV, Pryor DI, Burmeister E, et al. Results of a prospective study of positron emission tomography-directed management of residual nodal abnormalities in node-positive head and neck cancer after definitive radiotherapy with or without systemic therapy. Head Neck 2011;33:1675–1682. 11. Beswick DM, Gooding WE, Johnson JT, Branstetter BF 4th. Temporal patterns of head and neck squamous cell carcinoma recurrence with positron-emission tomography/computed tomography monitoring. Laryngoscope 2012;122:1512–1517. 12. McDermott M, Hughes MA, Rath T, et al. Negative predictive value of surveillance PET/CT in head and neck squamous cell cancer. Am J Neuroradiol 2013;34:1632–1636. 13. Shie P, Cardarelli R, Sprawls K, Fulda KG, Taur A. Systematic review: prevalence of malignant incidental thyroid nodules identified on fluorine-18 fluorodeoxyglucose positron emission tomography. Nucl Med Commun 2009;30:742–748.
Johnson and Branstetter: PET/CT in Head and Neck Oncology
915
