Two or three cycles of induction chemotherapy in locoregionally advanced nasopharyngeal carcinoma?

PURPOSE: To investigate the optimal cycles of induction chemotherapy (IC) in patients with locoregionally advanced nasopharyngeal carcinoma (LANPC). METHODS: We included LANPC patients treated with two or three IC cycles from January 2015 to December 2021. The chi-square test, Kaplan-Meier method, propensity score matching (PSM), and Multivariate Cox regression analyses were used for statistical analysis. RESULTS: A total of 491 patients were included in this study, of whom 166 (33.8%) received two cycles and 325 (66.2%) received three cycles of IC. Patients with stage IVA disease (P < 0.001), advanced T stage (P = 0.011), and advanced N stage (P < 0.001) were more likely to receive three cycles of IC. Cox proportional hazards regression analyses showed that the number of IC cycles was not associated with better survival outcomes. Patients who received three cycles of IC had comparable LRFS (HR 0.992, 95% CI 0.525-1.875, P = 0.981), DMFS (HR 0.805, 95% CI 0.511-1.092, P = 0.351), PFS (HR 0.917, 95% CI 0.633-1.328, P = 0.645) and OS (HR 0.880, 95% CI 0.552-1.402, P = 0.590) compared to those with two cycles of IC. Similar results were found after PSM. No significant differences were found in the incidence of Grade 3-4 acute toxicities between the two and three-cycle groups. However, three cycles of IC significantly increased the incidence of Grade 1-2 leukopenia (P = 0.001), neutropenia (P = 0.015), anemia (P = 0.017), and vomiting (P = 0.024) compared to two cycles of IC. CONCLUSIONS: The number of IC cycles (two or three) did not seem to affect the survival outcome of LANPC patients in this retrospective analysis. However, three cycles of IC were associated with a higher incidence of mild to moderate acute toxicities. Prospective studies in well-defined patient groups with a more uniform treatment program differing only in the number of IC cycles are warranted.