Value of PET scan in treatment decision making for nodal metastases in SCHNC-single institutional update

Abstract

6043 Background: Management of nodal neck disease in patients with SCHNC (squamous cell carcinoma of the head and neck) treated with CRT (chemoradiotherapy) remains controversial. We retrospectively evaluated the utility of PET scans in monitoring response to therapy and in determining the role of neck dissections (ND) in patients presenting with SCHNC stages N2b or higher, treated with combined CRT. Methods: A retrospective review of medical records of all patients treated at our institution with HNC Tx N2b, N2c or N3 between the years 2002–2007 was undertaken. IRB approval was obtained for this study. To be eligible for this analysis, patients must have had baseline and follow up PET scans at the end of CRT and prior to ND. Data regarding age, gender, primary tumor site, stage, baseline and follow up PET scan results, operative pathology of ND when performed, and local control were recorded. Results: Thirty-six eligible patients were identified. Median age was 56 (range: 37–84) years; M:F ratio: 30–6. Primary site of tumor was: Lip and oral cavity (n=4); Pharynx: n=28 (Tonsil: n=18; hypopharynx: n=2; BOT: n=5; oropharynx: n=3); Larynx: n=3. Stage distribution: IVa: n=32; IVb: n=4; Nodal stage: N2b: n=25; N2c: n=8; N3: n=3. At the first post CRT assessment: PET scan was negative at primary and nodal sites: n=25 (69%); positive at primary and nodal sites: n=11 (31%); primary site only: n=2; nodal site only: n=7; both primary and nodal site uptake: n=2. Twenty three of twenty five patients (92%) that were PET negative post CRT, remain in complete remission at a median follow up of 19 months. ND data are available in 9 of 11 patients that had a positive PET scan post CRT. Six of nine patients with positive post CRT PET had SCC noted in post CRT ND. Three of nine patients with positive PET had no disease found on ND, however, two of these three patients had a PET scan post CRT performed <8 weeks post completion of treatment. Conclusions: Post CRT PET scan negativity predicts for an extremely favorable outcome. To reduce false positive rates, follow up PET scans should be performed no sooner than 8 weeks post CRT. PET scan positivity after 8 weeks post CRT, either at the primary or nodal site, predicts high probability of persistent nodal disease detected during ND. No significant financial relationships to disclose.