Head and Neck Cancer
disease control in this study. A protracted time interval between CRT and surgical intervention may delay the treatment of persistent disease or increase morbidity related to surgery after the onset of fibrosis in the neck.
An initial meta-analysis of the role of PET alone for detecting residual or recurrent head and neck cancer demonstrated greater sensitivity for scans performed 10 or more weeks after treatment.13
With the improved accuracy of combined PET-CT over PET alone, recent studies utilizing the combined imaging modality have demonstrated that a negative scan performed within six to eight weeks of completion is highly accurate (NPV 94–100%) for cervical lymph nodes.11,23
Other
investigators recommend waiting until approximately 10 to 12 weeks after CRT in order to optimize PET-CT sensitivity and specificity, while still allowing adequate time for surgical intervention before the onset of extensive tissue fibrosis.1,3,13,20
Wide variability in the timing of scanning
within each of these studies may affect the overall predictive values for post-treatment PET-CT.
The authors recommend an algorithm for patient management after CRT that comprises physical examination four to six weeks after completion of treatment to assess initial disease response, followed shortly thereafter by imaging with contrast-enhanced CT and PET-CT (see Figure 3). In order to prevent an unnecessary delay in identifying and treating residual disease, imaging should be performed no later than 12 weeks after the completion of treatment, with a preference towards earlier imaging (at eight weeks).
If the results of the physical examination or the imaging studies are suggestive of persistent or progressive disease, appropriate surgical intervention should be performed. Ideally, the assessment of treatment
1. Schöder H, Fury M, Lee N, et al., PET monitoring of therapy response in head and neck squamous cell carcinoma, J Nucl Med, 2009;50:74S–88S.
2. Yao M, Smith RB, Graham MM, et al., The role of FDG PET in management of neck metastasis from head-and-neck cancer after definitive radiation treatment, Int J Radiat Oncol Biol Phys, 2005;63:991–9.
3. Ong SC, Schöder H, Lee NY, et al., Clinical utility of 18F-FDG PET/CT in assessing the neck after concurrent chemoradiotherapy for locoregional advanced head and neck cancer, J Nucl Med, 2008;49:532–40.
4. Wahl R, Jacene H, Kasamon Y, et al., From RECIST to PERCIST: Evolving considerations for PET response criteria in solid tumors, J Nucl Med, 2009;50:122S–50S.
5. Baek C, Chung MK, Son YI, et al., Tumor volume assessment by 18F-FDG PET/CT in patients with oral cavity cancer with dental artifacts on CT and MR images, J Nucl Med, 2008;49:1422–8.
6. Seol Y, Kwon BR, Song MK, et al., Measurement of tumor volume by PET to evaluate prognosis in patients with head and neck cancer treated by chemoradiation therapy, Acta Oncol, 2010;49:201–8.
7. La T, Filion EJ, Turnbull BB, et al., Metabolic tumor volume predicts for recurrence and death in head-and-neck cancer, Int J Radiat Oncol Biol Phys, 2009;74:1335–41.
8. Chung M, Jeong HS, Son YI, et al., Metabolic tumor volumes by [18F]-fluorodeoxyglucose PET/CT correlate with occult metastasis in oral squamous cell carcinoma of the tongue, Ann Surg Oncol, 2009;16:3111–7.
9. Schöder H, Yeung HW, Gonen M, et al., Head and neck cancer: clinical userfulness and accuracy of PET/CT image fusion,
Radiology, 2004;231:65–72.
10. Branstetter BF 4th, Blodgett TM, Zimmer LA, et al., Head and neck malignancy: is PET/CT more accurate than PET or CT alone?, Radiology, 2005;235:580–6.
11. Malone JP, Gerberi MA, Vasireddy S, et al., Early prediction of response to chemotherapy for head and neck cancer: reliability of restaging with combined positron emission tomography and computed tomography, Arch Otolaryngol Head Neck Surg, 2009;135:1119–25.
12 Chen AY, Vilaseca I, Hudgins PA, et al., PET-CT vs contrast- enhanced CT: what is the role for each after chemoradiation for advanced oropharyngeal cancer?, Head Neck, 2006;28:487–95.
13. Isles MG, McConkey C, Mehanna HM, A systematic review and meta-analysis of the role of positron emission tomography in the follow up of head and neck squamous cell carcinoma following radiotherapy or chemoradiotherapy, Clin Otolaryngol, 2008;33:210–22.
14. Frank DK, Hu KS, Culliney BE, et al., Planned neck dissection after concomitant radiochemotherapy for advanced head and neck cancer, Laryngoscope, 2005;115:1015–20.
15. Stenson KM, Haraf DJ, Pelzer H, et al., The role of cervical lyphadenectomy after aggressive concomitant chemoradiotherapy: the feasibility of selective neck dissection, Arch Otolaryngol Head Neck Surg, 2000;126:950–6.
16. Brizel DM, Prosnitz RG, Hunter S, et al., Necesity for adjuvant neck dissection in setting of current chemoradiation for advanced head-and-neck cancer, Int J Radiat Oncol Biol Phys, 2004;58:1418–23.
17. Nayak JV, Walvekar RR, Andrade RS, et al., Deferring planned
response should be performed in a collaborative environment with input from the patient’s head and neck surgeon, medical oncologist, radiation oncologist and radiologist. The multidisciplinary setting provides the best context for interpreting the extent of disease response based on clinical and radiologic findings. It also enables the team to determine the direction for further patient management.
Conclusion
CRT for organ preservation in patients with advanced-stage head and neck cancer produces an excellent locoregional response rate. The addition of functional imaging (PET) to the traditional structural imaging methods (physical exam, CT, and MRI) has substantially improved the management of patients with advanced-stage head and neck cancer after CRT. It has also reduced the morbidity associated with routine surgical intervention regardless of clinical response.
The use of PET-CT with its high NPV has become a reliable tool for helping to determine which patients have achieved a complete tumor response at the primary tumor site and cervical lymph nodes. Patients with a negative post-treatment PET-CT and no evidence of disease on physical examination should be considered for observation rather than planned neck dissection.
There is some disagreement among investigators as to the exact timing of PET-CT after the completion of CRT. Although early PET-CT (after six to eight weeks) maintains a high NPV, there is a higher likelihood of false-positive findings and thus a lower PPV than scans performed longer (12 weeks) after treatment.
Ultimately, clinicians must strive to achieve a balance between timely and accurate assessments of tumor response and preventing the risks associated with delaying the treatment of persistent disease. n
neck dissection following chemoradiation for stage IV head and neck cancer: the utility of PET-CT, Laryngoscope, 2007;117:2129–34.
18. Yao M, Graham MM, Hoffman HT, et al., The role of post- radiation therapy FDG-PET in prediction of necessity of post- radiation therapy neck dissection in locally advanced head- and-neck squamous cell carcinoma, Int J Radiat Oncol Biol Phys, 2004;59:1001–10.
19. Goguen LA, Posner MR, Tishler RB, et al., Examining the need for neck dissection in the era of chemoradiation therapy for advanced head and neck cancer, Arch Otolaryngol Head Neck Surg, 2006;132:526–31.
20. Wang YF, Liu RS, Chu PY, et al., Positron emission tomography in surveillance of head and neck squamous cell carcinoma after difinitive chemoradiotherapy, Head Neck, 2009;31:442–51.
21. Gourin CG, Williams HT, Seabolt WN, et al., Utility of positron emission tomography-computed tomography in identification of residual disease after chemoradiation for advanced head and neck cancer, Laryngoscope, 2006;116:705–10.
22. Goerres GW, Schmid DT, Bandhauer F, et al., Positron emission tomography in the early follow-up of advanced head and neck cancer, Arch Otolaryngol Head Neck Surg, 2004;130:105–9.
23. Rabalais AG, Walvekar R, Nuss D, et al., Positron emission tomography-computed tomography surveillance for the node- positive neck after chemoradiography, Laryngoscope, 2009;119:1120–4.
24. Malone J, Robbins KT, Neck dissection after chemoradiation for carcinoma of the upper aerodigestive tract: indications and complications, Curr Opin Otolaryngol Head Neck Surg, 2010;18(2):89–94.
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