Benefit of chemotherapy in stage III nasopharyngeal carcinoma: Analysis of the surveillance, epidemiology, and end results database.

Objectives: Chemoradiotherapy is the standard treatment for locoregionally advanced nasopharyngeal carcinoma (NPC). We aimed to reveal factors associated with chemotherapy use and evaluate chemotherapy's benefit in patients with stage III NPC stratified by lymph node status.

Patients And Methods: Overall, 1452 patients with stage III NPC who underwent radiotherapy with (n = 1361) or without (n = 91) chemotherapy were identified in the SEER database. We examined predictors for chemotherapy use using logistic regression analysis. We compared all-cause mortality (ACM) and cancer-specific mortality (CSM) using the Kaplan-Meier method. Cox regression and competing risk analyses were used to evaluate the benefit of chemotherapy. The inverse probability of treatment weighting (IPTW) approach was applied to reduce selection bias and adjust for competing risks. Subgroup analyses and interaction effects were explored.

Results: Factors including age, sex, insured status, tumor grade, and N category were associated with chemotherapy use. Chemotherapy was associated with decreased 5-year ACM (31.4% vs. 48.4%, p < 0.001) and CSM (25.5% vs. 35.8%; p = 0.017) in stage III NPC patients. The IPTW-adjusted hazard ratio for 5-year ACM was 0.57 (95% CI: 0.38-0.86, p = 0.008), whereas IPTW-adjusted sub-hazard ratio for 5-year CSM was 0.62 (95% CI: 0.42-0.93, p = 0.003). A significant interaction effect existed between lymph node status and treatment modality. Chemotherapy offered a significant survival benefit in node-positive stage III NPC. However, no chemotherapy benefit for the node-negative disease was observed.

Conclusion: Chemotherapy adds survival benefit in stage III NPC, especially in patients with node-positive disease. The magnitude of chemotherapy benefit in node-negative stage III NPC warrants further investigation.