Prognostic model for survival of local recurrent nasopharyngeal carcinoma with intensity-modulated radiotherapy

Background: Intensity-modulated radiotherapy (IMRT) is the main salvage treatment for advanced locally recurrent nasopharyngeal carcinoma (NPC); however, survival outcomes vary. We aimed to construct a prognostic-score model to identify patients who could benefit from salvage IMRT. Methods: This retrospective study involved 251 patients with locally recurrent NPC. The following parameters were analysed following IMRT: patient performance status, age, gender, late complications, T-stage of recurrence, synchronous nodal recurrence, primary gross tumour volume (GTV-nx), disease-free interval, re-irradiation dose and chemotherapy. The model was based on the hazard ratio coefficients of six significantly negative prognostic factors for survival. Results: Significantly negative prognostic factors included Karnofsky Performance Status <= 70, age >50 years, late complications, recurrent T3-4 stage, synchronous nodal recurrence and GTV-nx >30cm(3). Three subgroups were defined according to model scores: low risk (0-4), intermediate risk (5-8) and high risk (9-15). The 5-year overall survival rates were 64.3%, 32.2% and 7.7%, respectively. The main cause of death was radiation-induced complications. Conclusion: The prognostic-score model demonstrated that re-irradiation with IMRT is suitable for low-risk and intermediate-risk patients but may be unsuitable for high-risk patients. Further research into the protection of critical adjacent organs to reduce late complications in these patients is warranted.