Early restaging whole-body ¹⁸F-FDG PET during induction chemotherapy predicts clinical outcome in patients with locoregionally advanced nasopharyngeal carcinoma

Purpose: This study was undertaken to evaluate the utility of whole-body ¹⁸F-FDG PET in monitoring therapeutic effect during induction chemotherapy (IC) and in predicting prognosis in patients with locoregionally advanced nasopharyngeal carcinoma (NPC). Methods: Fifty patients who had histologically proven, locoregionally advanced NPC without distant metastasis and had received IC were recruited in this study. The study cohort consisted of 19 females and 31 males (age 17-72 years, mean 45.9±11.9). Whole-body ¹⁸F-FDG PET was performed in each patient after completion of one (33 patients) or two (17 patients) courses of IC. Each patient was restaged on the basis of the ¹⁸F-FDG PET results. Patients who were downstaged to stage I or II were classified as major responders; the rest were classified as non-major responders. Results: Only 1 of the 23 major responders subsequently developed local recurrence. At the time of data analysis, all major responders were alive; by contrast, of the 27 non-major responders, 15 had locoregional recurrence or distant metastasis and nine had died (seven of NPC and two of treatment-related complications). Kaplan-Meier survival analysis showed significantly longer recurrence-free survival and overall survival in major responders (56.4±9.2 and 58.1±2.2 months) as compared with non-major responders (33.7±23.2 and 44.7±20.0 months), with p<0.0001 and p=0.0024, respectively. Conclusion: The results of this study suggest that early restaging by a single whole-body ¹⁸F-FDG PET scan after the first or second course of IC is useful for predicting therapeutic response and outcome in patients with locoregionally advanced NPC.