The impact of the interval between the induction of chemotherapy and radiotherapy on the survival of patients with nasopharyngeal carcinoma

Background: There have been no reliable scientific studies examining whether the interval between induction chemotherapy (IC) and initiating radiotherapy is associated with poor outcomes of nasopharyngeal carcinoma (NPC). Patients and methods: In this retrospective study, we included a total of 239 local advanced NPC patients who underwent concurrent chemoradiotherapy and IC. Based on the interval between IC and intensity-modulated radiation therapy (IMRT), the patients were classified into three groups as follows: Group A (<= 7 vs >7 days), Group (<= 14 vs >14 days), and Group C (<= 21 vs >21 days). Univariate and multivariate regression analyses were performed to determine the prognostic factors of survival outcomes. The differences between the two groups were compared by the log-rank test. Results: The median IC-IMRT interval was 9 days (range, 1-76 days). The median follow-up time was 40 months (range, 4-58 months). The IC-IMRT interval including Group A, Group B, and Group C was not significantly associated with overall survival (OS), distant metastasis-free survival (DMFS), locoregional relapse-free survival (LRFS), or disease-free survival (DFS). Multivariate analysis showed that the tumor stage was the independent significant predictor for OS, DMFS, LRFS, and DFS. But it appears that there was a trend toward improvement in the outcome of <= 7 days group in OS from the Kaplan Meier curves. Conclusion: It is also feasible to postpone radiotherapy for 1-3 weeks if patients were unable to receive treatment immediately due to chemotherapy complications such as bone marrow suppression. However, we suggest that patients should start IMRT as soon as possible after IC.