Individualized number of induction chemotherapy cycles for locoregionally advanced nasopharyngeal carcinoma patients based on early tumor response.

BACKGROUND: The optimal number of cycles of induction chemotherapy (IC) in locoregionally advanced nasopharyngeal carcinoma (LANPC) is unclear. We aimed to combine the tumor response during IC and tumor stage to individualize the number of IC cycles. METHODS: Totally, 498 LANPC patients who received IC plus CCRT between 2014 and 2018 were reviewed. Tumor response during IC was used to stratify patients with different risks. All patients were classified into those who received two cycles of IC and those who were treated with three cycles. Propensity score matching methods were performed to compare the treatment efficiency. RESULTS: After two cycles of IC, 340/498 (68.3%) cases showed complete tumor response (CR)/partial response (PR) and 158 (31.7%) achieved stable disease (SD)/disease progression (PD). Unfavorable responders (SD/PD) exhibited poor survival outcomes. The three-cycle IC regimen was correlated with better OS and PFS than the two-cycle regimen for N2-3 patients in the CR/PR group. However, the use of different IC cycle strategies achieved similar survival outcomes for SD/PD or N0-1 patients. The incidences of acute toxicities were higher in the IC = 3 group. CONCLUSIONS: Tumor response during IC could be a powerful predictor of LANPC and could be used to guide the individualized number of IC cycles. A three-cycle IC regimen seemed to be preferable for N2-3 patients who received CR/PR during IC. However, an additional cycle of IC could not benefit N0-1 or SD/PD patients, and the optimal treatment strategies for these patients require further consideration.