Usefulness of interim FDG-PET after induction chemotherapy in patients with locally advanced squamous cell carcinoma of the head and neck receiving sequential induction chemotherapy followed by concurrent chemoradiotherapy.

PURPOSE: Induction chemotherapy (ICT) has been used to select patients for organ preservation and determine subsequent treatments in patients with locally advanced squamous cell carcinoma of the head and neck (LASCCHN). Still, the clinical outcomes of LASCCHN patients who showed response to ICT are heterogeneous. We evaluated the efficacy of interim 18-fluoro-2-deoxy-glucose positron emission tomography (FDG-PET) after ICT in this specific subgroup of LASCCHN patients who achieved partial response (PR) after ICT to predict clinical outcomes after concurrent chemoradiotherapy (CCRT).

METHODS AND MATERIALS: Twenty-one patients with LASCCHN who showed PR to ICT by Response Evaluation Criteria In Solid Tumors before definitive CCRT were chosen in this retrospective analysis. FDG-PET was performed before and 2-4 weeks after ICT to assess the extent of disease at baseline and the metabolic response to ICT, respectively. We examined the correlation of the metabolic response by the percentage decrease of maximum standardized uptake value (SUVmax) on the primary tumor or lymph node after ICT or a specific threshold of SUVmax on interim FDG-PET with clinical outcomes including complete response (CR) rate to CCRT, progression-free survival (PFS), and overall survival (OS).

RESULTS: A SUVmax of 4.8 on interim FDG-PET could predict clinical CR after CCRT (100% vs. 20%, p=0.001), PFS (median, not reached vs. 8.5 mo, p<0.001), and OS (median, not reached vs. 12.0 months, p=0.001) with a median follow-up of 20.3 months in surviving patients. A 65% decrease in SUVmax after ICT from baseline also could predict clinical CR after CCRT (100% vs. 33.3%, p=0.003), PFS (median, not reached vs. 8.9 months, p<0.001) and OS (median, not reached vs. 24.4 months, p=0.001) of the patients.

CONCLUSION: These data suggest that interim FDG-PET after ICT might be a useful determinant to predict clinical outcomes in patients with LASCCHN receiving sequential ICT followed by CCRT.