We evaluated the effectiveness of combined intra-arterial chemotherapy and radiotherapy on head and neck squamous cell carcinomas using fluorodeoxyglucose (FDG) PET.
Methods: Fifteen patients with squamous cell carcinoma of the head and neck were included in the study. Fourteen patients completed the treatment regimen and underwent FDG PET before and 4 wk after chemoradiotherapy. One patient underwent pretreatment FDG PET only. The pretreatment and post-treatment PET images were compared with clinical and histopathologic evaluations of the effects of chemoradiotherapy. For the quantitative evaluation of regional radioactivity, standardized uptake values (SUVs) with an uptake period of 50 min were used.
Results: Before treatment, FDG PET detected neoplasms in all 15 patients. The overall clinical response rate to chemoradiotherapy in the 14 patients who were imaged before and after treatment was 100%. Before treatment, the neoplastic lesions showed high SUVs (mean 7.77 mg/mL), which significantly decreased after therapy (3.62 mg/mL, P < 0.01). Lesions with higher pretreatment SUVs (> 7 mg/mL) showed residual viable tumor cells after the treatment in 3 of 8 patients, whereas those with lower SUVs (< 7 mg/mL, 6 patients) were successfully treated. Three of seven tumors with post-treatment SUVs > 4 mg/mL had viable tumor cells, whereas all tumors (7/7) with post-treatment SUVs < 4 mg/mL showed no viable cells. With concomitant chemoradiotherapy monitored by FDG PET, 5 patients avoided surgery entirely, and the remaining 9 patients underwent a reduced form of surgery.
Conclusion: FDG PET is useful in evaluating the effects of combined chemotherapy and radiotherapy in patients with head and neck carcinoma. Pretreatment FDG PET is useful in predicting the response to treatment, and post-treatment FDG PET can evaluate residual viable cells. Hence, FDG PET is a valuable tool in the treatment of head and neck tumors.