Determination of optimum number of cycles of induction chemotherapy for locoregionally advanced nasopharyngeal carcinoma: a single-center retrospective study.

BACKGROUND: Induction chemotherapy (IC) followed by concurrent chemo-radiotherapy (CCRT) is the current standard of care for locoregionally advanced nasopharyngeal carcinoma (LA-NPC) patients. However, there is still no consensus on the optimum number of IC cycles. In this study, we aimed to assess the efficacy and toxicities of two or more cycles of IC for LA-NPC patients. METHODS: Data of LA-NPC patients consecutively treated with IC followed by concurrent chemo-radiotherapy (CCRT) in our institute from 2017 to 2022 were retrospectively retrieved and analyzed. Survival outcomes of patients who received two IC cycles were compared with those who received more than two IC cycles. Univariate and multivariate Cox regression analysis were then performed to determine factors that could be independent predictors of survival. Chi-square test and Fisher's exact test were used to compare treatment associated acute toxicities between the two groups. RESULTS: A total of 125 patients were recruited in this study. There were 89 patients who received 2 cycles (IC = 2) of IC and 36 received more than 2 cycles (IC > 2) of IC. The median follow-up time was 26 months [IQR 16-38]. The 3-year overall survival rate was not statistically significant between the two groups (95.50% vs. 86.11%, P = 0.501). Similarly, loco-regional recurrence free survival and progression free survival were not significant (97.75% vs. 97.22%, P = 0.694; and 88.76% vs. 83.33%, P = 0.129), but distant metastasis free survival was significant (88.76% vs. 86.11%, P = 0.049). Multivariate Cox regression analysis showed that IC regimen was an independent prognostic factor. CONCLUSIONS: Two cycles of IC is effective and more than two does not add any additional benefit to the survival outcomes of LA-NPC patients.