Adjuvant chemotherapy following combined induction chemotherapy and concurrent chemoradiotherapy improves survival in N2-3-positive nasopharyngeal carcinoma patients

Objective This study aimed to explore the clinical value of adjuvant chemotherapy (ACT) following concurrent chemo-radiotherapy (CCRT) and induction chemotherapy (ICT) in loco-regionally advanced nasopharyngeal carcinoma (LANC). Methods We included 839 newly diagnosed LANC patients in this study. ICT plus CCRT (ICT + CCRT group) was administered to 443 patients, and 396 patients received ACT after ICT plus CCRT (ICT + CCRT + ACT group). Univariate and multivariate Cox regression analyses were carried out. Furthermore, propensity score matching (PSM) was applied to balance the study and control groups. Results A total of 373 pairs of LANC patients were obtained after PSM analysis. We found that ACT following ICT + CCRT has no significant effect on improving the survival of LANC patients. By further exploring the ICT + CCRT + ACT treatment protocol, we excluded N0-1-positive patients and re-performed PSM in the ICT + CCRT and ICT + CCRT + ACT groups. Each group consisted of 237 patients. Kaplan-Meier analysis revealed that there were differences between the ICT + CCRT and ICT + CCRT + ACT groups in terms of the 5-year overall survival (OS) (78.9% vs. 85.0%, P = 0.034), disease-free survival (DFS) (73.4% vs. 81.7%, P = 0.029), and distant metastasis-free survival (DMFS) (84.9% vs. 76.0%, P = 0.019). In addition, the ICT + CCRT + ACT group had a higher incidence of grade 3/4 acute leukocytopenia/neutropenia. Conclusion Compared with ICT + CCRT, ACT following ICT plus CCRT can reduce distant metastasis of N2-3-positive LANC and improve the OS and DFS. The results demonstrated the feasibility and clinical utility of ACT following ICT plus CCRT.