Factors contributing to the efficacy of concurrent-adjuvant chemotherapy for locoregionally advanced nasopharyngeal carcinoma: combined analyses of NPC-9901 and NPC-9902 Trials

Abstract

Background: The current standard treatment for locoregionally advanced nasopharyngeal carcinoma (NPC) was conventional-fractionation radiotherapy plus concurrent-adjuvant chemotherapy as recommended by the Intergroup-0099 Study. This combined analysis of the NPC-9901 and the NPC-9902 Trials aims to provide more comprehensive data to evaluate the efficacy of the Intergroup-0099 regimen and the contributing factors.

Methods: Eligible patients with stage III-IVB non-keratinizing NPC were randomly assigned to radiotherapy-alone (RT(i) group: 218 patients) or chemoradiotherapy (CRT(i) group: 223 patients) using cisplatin (100mg/m(2)) for three cycles in concurrence with radiotherapy, followed by cisplatin (80 mg/m(2)) plus fluorouracil (1000 mg/m(2)/day for 4 days) for three cycles. The median follow-up was 6.1 years.

Findings: Comparison by intention-to-treat showed that the CRT(i) group achieved significant improvement in overall failure-free rate (FFR), locoregional-FFR and cancer-specific survival (p ≤ 0.019); but the improvements for distant-FFR and overall survival (OS) were statistically insignificant (p ≥ 0.14). Further exploratory studies based on actual treatment showed that an additional improvement achieved was a significant gain in OS (CRT(a) versus RT(a) group: 72% versus 63% at 5-year, p=0.037). Multivariate analyses showed that the dose of cisplatin during the concurrent phase had significant impact on locoregional-FFR and OS, while that of fluorouracil during the adjuvant phase was significant for distant-FFR. The 5-year locoregional-FFR for patients who received 0-1, 2 and 3 concurrent cycles were 79%, 88% and 88%, respectively; the corresponding distant-FFR by adjuvant cycles were 68%, 78% and 77%, respectively.

Interpretation: Our results support the current practice of adding concurrent cisplatin plus adjuvant cisplatin-fluorouracil to radiotherapy for treating patients with locoregionally advanced NPC. The concurrent phase is important for locoregional control and survival, cisplatin 200mg/m(2) in two concurrent cycles might be adequate. Additional chemotherapy using fluorouracil-containing combination contributed to improving distant control.