Abstract
Objective: Understand local, nodal, and distant cure rates and the prognostic value of [18F]Fluorodeoxyglucose positron emission tomography (PET-CT) after chemoradiation (CRT) for advanced oropharyngeal squamous cell carcinoma (OPSCC). Propose a potential algorithm for surveillance PET-CT based on patient history.
Method: A retrospective chart review of 53 patients treated from 2005 to 2008 with CRT for stage 3 (6%) or stage 4 (94%) OPSCC at a tertiary referral center. Variables reviewed included type of CRT, PET-CT results, and smoking history. Outcomes evaluated included patterns of recurrence, survival, and progression free survival (PFS).
Results: Overall PFS rate was 77% at 3 years. The first post-treatment PET-CT obtained a median of 2.3 months after CRT was normal in 32 patients, however 5 patients ultimately relapsed. Sixteen patients had elevated FDG uptake of which 3 recurred. The result of the first PET-CT was not significantly associated with recurrence (P = .2988). The second post-treatment PET-CT, obtained a median of 8.6 months after CRT, was normal in 28 patients, of which only one relapsed. Four out of 12 patients with abnormal scans recurred. A normal delayed PET-CT predicted the absence of disease (P = .0211).
Conclusion: A normal PET-CT early after CRT for OPSCC did not reflect the absence of disease. A normal PET-CT 6 to 8 months after treatment predicted good control of disease. The optimal time for PET-CT to demonstrate prognostic value may be 6 to 8 months after completion of CRT.
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