A Pilot Study Comparing FLT-PET and FDG-PET in the Evaluation of Response to Cetuximab and Radiation Therapy in Advanced Head and Neck Malignancies

Abstract

Background: We prospectively compared FLT-PET and FDG-PET in evaluating response to cetuximab and chemoradiotherapy for HNSCC. Methods: Six patients with HNSCC received cetuximab followed by chemoradiotherapy. Patients had FLTand FDG-PET scans at baseline, after cetuximab, and 2 weeks into chemoradiotherapy. Changes in SUVmax on successive scans were compared to baseline. Results: After induction therapy, changes in SUVmax ranged from -2 to 32% for FLT-PET and -24 to 0% for FDGPET. After two weeks of chemoradiotherapy, changes in SUVmax ranged from -71 to 9% for FLT-PET and -80 to -7% for FDG-PET. One patient experienced consecutive increases in FLT uptake not detected by FDG-PET. No patient recurred at a median 14.6 months. Conclusions: Functional imaging early during definitive therapy for HNSCC is feasible. Similar changes in FLT and FDG uptake are detected during chemoradiotherapy; however, distinct differences were seen after induction cetuximab therapy. Further follow-up will facilitate correlation of radiotracer uptake with clinical outcome.