Efficacy of chemoradiotherapy in survival of stage Ⅳ nasopharyngeal carcinoma and establishment of a prognostic model.

The efficacy of chemoradiotherapy regimen in the treatment of stage Ⅳ nasopharyngeal carcinoma (Ⅳ NPC) is not clear. This retrospective study aimed to reveal the benefit of chemoradiotherapy in Ⅳ-NPC and to develop a survival prognostic model for the disease prediction.The Surveillance, Epidemiology, and End Results (SEER) database at https://seer.cancer.gov was retrieved for stage Ⅳ NPC patients between 2004 and 2016. The patients were divided into two groups of radiotherapy and chemoradiotherapy according to the treatment method. Overall survival (OS) and cancer-specific survival (CSS) between the groups were compared using Kaplan-Meier analysis, log-rank test, and propensity matching score (PSM). Cox proportional hazards model, nomogram, and receiver operating characteristic (ROC) curve were employed to establish the prognostic model.A total of 729 patients with Ⅳ NPC were introduced, of whom 44 received radiotherapy and 685 received chemoradiotherapy. Results of statistical tests demonstrated that chemoradiotherapy was associated with improved OS and CSS, especially in the patients with ⅣA NPC (P < 0.05); further multivariate analysis with PSM confirmed that chemoradiotherapy benefited the patients' OS (HR: 0.24, 95% CI: 0.12-0.50; P < 0.001). Moreover, the efficacy of chemoradiotherapy was found significantly correlated to metastasis. Even though chemoradiotherapy had an obvious survival benefit in patients without metastasis, it only helped to improve the CSS in those with metastases.This study indicated that chemoradiotherapy could improve the survival of NPC patients at stage ⅣA and non-metastasis. The nomogram we established may provide reference for clinical treatment of NPC.