Optimize the number of cycles of induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma: a propensity score matching analysis.

There is no conclusive on the optimal number of cycles of induction chemotherapy (IC) with the greatest benefit to patient survival. This study aimed to assess the efficiency and acute toxicities of different cycles of IC for patients with locoregionally advanced nasopharyngeal carcinoma (LA-NPC). We reviewed data from patients with LA-NPC treated with IC plus concurrent chemoradiation (CCRT). Propensity score matching (PSM) was applied to match paired patients. After PSM, survival outcomes of matched patients were compared between two and three cycles of IC groups. Univariate and multivariate Cox regression analysis were carried out to identify potentially independent predictors. Treatment-related acute toxicities between the two groups were compared by Pearson X test or Fisher's exact test. In total, 189 pairs were selected. The median follow-up time was 60 months (range 5 to 126 months). There was no difference between two and three cycles of IC in terms of 5-year overall survival (87.0% vs. 89.7%, p = 0.991), distant metastasis-free survival (90.1% vs. 86.8%, p = 0.587), locoregional recurrence-free survival (97.0% vs. 93.8%, p = 0.488), or progression-free survival (79.4% vs. 79.3%, p = 0.896). Multivariate Cox analysis showed that T stage, N stage, and clinical stage were independent prognostic factors. Three cycles of IC were associated with a higher incidence of Grade 1-2 acute toxicity than two cycles during IC period. The efficacy of two cycles of IC achieved similar survival outcomes as three cycles and has a lower incidence of treatment-related acute toxicity.