Induction versus adjuvant chemotherapy combined with concurrent chemoradiotherapy in locoregionally advanced nasopharyngeal carcinoma: a retrospective cohort study

Background: Currently available evidence favors the combination of chemotherapy with concurrent chemoradiotherapy in locoregionally advanced nasopharyngeal carcinoma (LANPC). However, the optimal timing for additional chemotherapy is unclear. This study was conducted to compare the efficacy and toxicity of induction chemotherapy plus concurrent chemoradiotherapy (IC+CCRT) versus concurrent chemoradiotherapy plus adjuvant chemotherapy (CCRT+AC). Methods: Two medical centers in China enrolled patients with LANPC (stage III-IVB) between January 2009 and May 2020. Through the use of propensity score matching (PSM), baseline characteristics were balanced. The primary endpoint was overall survival (OS), which was evaluated by the Kaplan-Meier method and log-rank test. Potential independent prognostic factors were identified using univariate and multivariate Cox proportional hazard analyses. Based on the chi-squared test, we compared the adverse events associated with treatment between the groups. Results: After the implementation of PSM, 159 patients treated with IC+CCRT and 72 patients treated with CCRT+AC were eventually enrolled in this study. There was no significant difference between patients treated with IC+CCRT and CCRT+AC in terms of 3-year OS (94.7% versus 90.9%, p=0.816), progression-free survival (PFS) (91.2% versus 83.1%, p=0.588), locoregional recurrence-free survival (LRFS) (92.5% versus 81.8%, p=0.478), or distant metastasis-free survival (DMFS) (93.4% versus 88.2%, p=0.783). There was no prognostic significance of the treatment for OS, PFS, LRFS, or DMFS (all p > 0.05) in the univariate and multivariate analyses. Patients treated with CCRT+AC had a higher incidence of grade 3 to 4 leucopenia (p=0.001) and neutropenia (p=0.001) than those treated with IC+CCRT. Conclusions: IC plus CCRT achieved comparable survival outcomes to CCRT plus AC and had a lower incidence of toxicity.