Long-term outcomes and prognostic factors of re-irradiation for locally recurrent nasopharyngeal carcinoma using intensity-modulated radiotherapy

Abstract

Aims: To analyse the outcomes and to evaluate the prognostic factors involved in the re-irradiation of locally recurrent nasopharyngeal carcinoma (NPC) using intensity-modulated radiotherapy (IMRT).

Materials and methods: A retrospective analysis of 239 NPC patients with local recurrence who were re-irradiated with IMRT between 2001 and 2008 was conducted. The distribution of disease re-staging was 5.4% for stage I, 18.4% for stage II, 29.7% for stage III and 46.4% for stage IV. Cisplatin-based chemotherapy was administered to 117 patients (49.0%) in addition to the IMRT.

Results: The mean D(95) and the V(95) of the gross tumour volume (GTV) were 66.78 Gy and 98.61%, respectively. The mean dose to the GTV was 70.04 Gy (61.73-77.54 Gy). The 5 year overall survival, local recurrence-free survival, distant metastasis-free survival and disease-free survival were 44.9, 85.8, 80.6 and 45.4%, respectively. In a univariate analysis, patient age, recurrent T (rT), recurrent N (rN), recurrent stage, tumour volume, mean dose and mean fractional dose of the GTV were significant prognostic factors for overall survival. In a multivariate analysis, only patient age, rN stage, recurrent stage, mean fractional dose and tumour volume remained significant for overall survival.

Conclusions: Re-irradiation using IMRT is available to improve local tumour control and to prolong patients' survival. A smaller tumour volume, higher fractional dose, younger patient ages, lower rN(0) stage and early recurrent stage are all independent prognostic factors for overall survival of recurrent NPC. It is of clinical importance to select the appropriate recurrent NPC cases for salvage re-irradiation by IMRT.