Exploratory Study of NPC-0501 Trial: Optimal Cisplatin Dose of Concurrent and Induction/Adjuvant Chemotherapy for Locoregionally Advanced Nasopharyngeal Carcinoma

Purpose: The current recommendation for patients with locoregionally advanced nasopharyngeal carcinoma (NPC) is cisplatin-based induction chemotherapy (IC) or adjuvant chemo-therapy (AC) plus concurrent chemoradiotherapy (CRT). However, data on the optimal platinum doses for each phase of combined regimens are lacking. Experimental Design: 742 patients with NPC in the NPC-0501 trial treated with CRT plus IC/AC and irradiated with intensity-modulated radiotherapy (IMRT) were analyzed. The optimal plat-inum dose to achieve the best overall survival (OS) in the concurrent and induction/adjuvant phases was studied. Results: Evaluation of the whole series shows the optimal platinum dose was 160 mg/m(2) in the concurrent and 260 mg/m(2) in the induction/adjuvant phase. Repeating the analyses on 591 patients treated with cisplatin throughout (no replacement by carboplatin) confirmed the same results. The cohort with optimal platinum doses in both phases had better OS than the cohort suboptimal in both phases (stage III: 90% vs. 75%; stage IVA-B: 80% vs. 56%, at 5-year). Multivariable analyses confirmed optimal platinum doses in both phases versus suboptimal dose in each phase are significant independent factors for OS, with HR of 0.61 [95% confidence interval (CI), 0.41-0.91] and 0.67 (95% CI, 0.48-0.94), respectively. Treatment sequence was statistically insignificant after adjusting for platinum doses. Conclusions: Both concurrent and IC/AC are needed for locor-egionally advanced NPC, even for patients irradiated by IMRT; the concurrent platinum dosage could be set at >= 160 mg/m(2) when coupled with adequate induction/adjuvant dosage at >= 260 mg/m(2) (or at least >= 240 mg/m(2)). To achieve these optimal dosages, IC-CRT at conventional fractionation is favored.