Do All Patients with Locoregionally Advanced Nasopharyngeal Carcinoma Benefit from the Maintenance Chemotherapy Using S-1/capecitabine?

Background: The goal of this study was to explore the benefits of S-1/capecitabine as maintenance therapy in locoregionally advanced nasopharyngeal carcinoma (NPC) patients with different risks of treatment failure. Methods: A total of 2205 eligible, locoregionally advanced NPC patients were recruited for this retrospective study. Multivariate Cox regression analysis was performed to identify optimal predictors of overall survival (OS) and distant metastasis-free survival (DMFS) for constructing the nomograms. Patients were stratified into high-risk or low-risk groups based on the total score of the nomograms. Propensity score matching (PSM) was performed to match the maintenance and non-maintenance cohorts in different risk groups. A log-rank test was performed to evaluate correlations between maintenance therapy and survival. Results: A nomogram for OS was established (C-index, 0.664; 95% confidence interval, 0.635-0.693). The 5-year OS rate was significantly higher in the low-risk group than in the high-risk group (83.5% vs. 67.2%, P < 0.001). Patients in the high-risk group who received S-1/capecitabine maintenance therapy achieved significant improvement in the 5-year OS rate (82.8% vs. 67.1%, p = 0.034), whereas patients in the low-risk group did not (86.7% vs. 80.9%, P = 0.081). There was no significant difference in OS, DMFS, progression-free survival (PFS), or toxicities between the 5-1 and capecitabine groups (all P > 0.05), and overall treatment-related adverse events (AEs) were not severe (grade 1-2). Conclusion: S-1/capecitabine maintenance therapy could prolong OS for locoregionally advanced NPC patients in the high-risk group. The toxicities of S-1/capecitabine maintenance therapy were mild and tolerable. Our findings can help guide maintenance therapy in locoregionally advanced NPC.