The feasibility of reduced-dose radiotherapy in childhood nasopharyngeal carcinoma with favorable response to neoadjuvant chemotherapy.

Abstract

To assess the feasibility of adjusting radiation dose (RD) in childhood NPC with favorable tumor response after neoadjuvant chemotherapy (NAC). Using an NPC-specific database, children and adolescents (≤18 years) with locoregionally advanced NPC (CA-LANPC) were retrospectively analyzed. Enrolled patients were those who received favorable tumor response after 2-4 cycles of NAC followed by concurrent chemoradiotherapy. Survival outcomes and treatment-related toxicities were compared for the standard RD on primary tumors (PT-RD_standard, 66-72 Gy) and the reduced RD on primary tumors (PT-RD_reduced, 60-65.9 Gy). A total of 132 patients were included, and the median follow-up time was 75.2 months (IQR, 53.2-98.7 months) for the entire cohort. The PT-RD_reduced group had a significantly decreased incidence of severe mucositis (51.3 % vs 32.1 %; P = 0.034) when compared to the PT-RD_standard group. The total incidence of severe sequela in the PT-RD_standard group were significantly higher than those in the PT-RD_reduced group (31.8 % vs 13.7 %; P = 0.029). In the propensity-matched analysis, the PT-RD_reduced group resulted in parallel 5-year survival with the PT-RD_standard group from the matched cohort (disease-free survival, 82.7 % vs 80.3 %, P = 0.841; overall survival, 91.7 % vs 91.3 %, P = 0.582; distant metastasis-free survival, 87.5 % vs 82.8 %, P = 0.573; and locoregional relapse-free survival, 95.6 % vs 97.3 %, P = 0.836). In multivariate analysis, the impact of PT-RD_reduced on all survival end points remained insignificant. Chemoradiotherapy with RD at levels of 60-65.9 Gy may be a reasonable strategy for CA-LANPC with favorable tumor response after NAC.