Assessment of early tumor response to induction chemotherapy (IC) in locally advanced squamous-cell carcinoma of head and neck (LASCCHN) with 18FDG PET-CT: A prospective trial.

Abstract

6017 Background: Response to IC with triplet regimens adding taxanes to cisplatin and 5-fluorouracil (TPF), followed by chemoradiotherapy (CRT) for LASCCHN, is usually evaluated after 2 cycles of IC, based on bidimensional WHO or modified WHO criteria. Concerns regarding toxicity profile of TPF suggest a potential benefit of an early response evaluation approach that could select patients who would be spared from a toxic regimen and promptly started on an alternative treatment. The aim of this study is to assess the ability of evaluating early response after the first IC cycle based on a 40% decrease in standard-uptake value (SUV) measured by 18 FDG PET-CT on the 14th day. Methods: Patients with LASCCHN who underwent IC with TPF were prospectively evaluated. Staging procedure included locoregional and chest imaging, endoscopic examination and FDG PET-CT. At day 14 of first cycle, a second FDG PET-CT was performed and treating physicians were blinded for these findings. All cases were conducted according to the usual post-cycle 2 WHO or modified WHO criteria evaluation. Written informed consent was obtained from all recruited patients. Results: Between February 2010 and October 2012, 40 stage III/IV LASCCHN patients (34 oropharyngeal, 3 hypopharyngeal and 3 laryngeal) were recruited. With a median follow up of 11.4 months the actuarial 2 years overall (OS) and disease free survival (DFS) of all patients were 81.4% and 69.2%, respectively. Responders (any decrease of SUV) at day 14 PET CT had a better OS (90 vs. 27% - p<0,001) and DFS (76 vs. 0% - p<0,001) as compared to non-responders. Decrease of at least 40% in the SUV of primary tumor predicted a better DFS (100 vs. 51% - p=0,007). Conclusions: These results suggest a potential role of early response evaluation with 18 FDG PET-CT in patients with LASCCHN undergoing IC. A SUV decrease of at least 40% predicts better DFS. An increase in the SUV predicts a poor prognosis.