Effect of adaptive replanning in patients with locally advanced nasopharyngeal carcinoma treated by intensity-modulated radiotherapy: a propensity score matched analysis.

PURPOSE: Limited data have been published regarding the effect of adaptive radiotherapy (ART) on clinical outcome in patients with nasopharyngeal carcinoma (NPC). We compared the long-term outcomes in patients with locally advanced NPC treated by adaptive intensity-modulated radiotherapy (IMRT) replanning versus IMRT.

METHODS: 200 NPC patients with stage T3/T4 were included between October 2004 and November 2010. Patients in both treatment groups were matched using propensity score matching method at the ratio of 1:1. Clinical outcomes were analyzed with Kaplan-Meier method, log-rank test and Cox regression.

RESULTS: After matching, 132 patients (66 patients in each group) were included for analysis. The median follow-up for the IMRT replanning group was 70 months, while the IMRT group was 69 months. The 5-year local-regional recurrence-free survival (LRFS) rate was higher in IMRT replanning group (96.7 vs. 88.1 %, P = 0.022). No significant differences in distant metastasis-free survival (DMFS), progression-free survival (PFS) and overall survival (OS) were observed between the two groups. 21.2 % patients in IMRT replanning group and 28.8 % patients in IMRT group had distant metastasis. In multivariable analysis, IMRT replanning was identified as an independent prognostic factor for LRFS (hazard ratio 0.229; 95 % CI 0.062-0.854; P = 0.028), but not for DMFS, PFS and OS.

CONCLUSIONS: IMRT replanning provides an improved LRFS for stage T3/T4 NPC patients compared with IMRT. Distant metastasis remains the main pattern of treatment failure. No significant advantage was observed in DMFS, PFS and OS when adaptive replanning was used.