Survival benefit of radiotherapy for metastatic nasopharyngeal carcinoma: a retrospective analysis based on SEER database

Objective To analyze survival benefits of radiotherapy in patients with nasopharyngeal carcinoma (NPC) with distant metastases and analyze relevant prognostic factors. Methods Medical records of 329 patients newly diagnosed with metastatic NPC screened from the Surveillance, Epidemiology and End Results (SEER) database (199 of 329 patients received radiotherapy) between 2010 and 2015 were retrospectively analyzed. Overall survival (OS) and disease-specific survival (DSS) were calculated by Kaplan-Meier curve. The effect of different clinicopathological factors on the clinical prognosis of metastatic NPC patients was evaluated by logrank test and Cox regression analysis. Results The median follow-up time was 12 months. The 3-and 5-year OS rates were 27.4% and 19.7%. The median OS was 17.9 months. Univariate analysis demonstrated that patients aged< 50 years, male, undifferentiated type, stage T3 or T4, positive regional lymph node, brain and liver metastases and 1-2 metastatic sites obtained OS and DSS benefits at 3 years after radiotherapy. Univariate and multivariate Cox analyses after propensity score matching showed that radiotherapy was an independent prognostic factor for metastatic NPC (OS, P=0.004; DSS, P=0.014). Besides, patients aged 60-69 years (OS, P=0.033; DSS, P=0.045), keratinizing squamous cell carcinoma (OS, P<0.05; DSS, P<0.05), stage T4(OS, P=0.002; DSS, P=0.024), 1-2 metastatic sites (OS, P=0.039; DSS, P=0.058), 3-4 metastatic sites (OS, P=0.003; DSS, P=0.005) and no chemotherapy (OS, P=0.000; DSS, P=0.000) had poor OS and DSS, whereas sex, race and degree of differentiation exerted no effect on OS and DSS. Conclusions Radiotherapy can significantly improve the OS and DSS of patients with metastatic NPC. Prospective and randomized controlled studies are required to further explore the role of radiotherapy in the management of metastatic NPC. Key words: Nasopharyngeal neoplasm/radiotherapy; Tumor metastasis; Prognosis