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

Background: To assess the feasibility of adjusting radiation dose (RD) in childhood NPC with favorable tumor response after neoadjuvant chemotherapy (NAC).

Patients And Methods: 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, 66-72 Gy) and the reduced RD on primary tumors (PT-RD, 60-65.9 Gy).

Results: 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 group had a significantly decreased incidence of severe mucositis (51.3 % vs 32.1 %; P = 0.034) when compared to the PT-RD group. The total incidence of severe sequela in the PT-RD group were significantly higher than those in the PT-RD group (31.8 % vs 13.7 %; P = 0.029). In the propensity-matched analysis, the PT-RD group resulted in parallel 5-year survival with the PT-RD 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 on all survival end points remained insignificant.

Conclusions: Chemoradiotherapy with RD at levels of 60-65.9 Gy may be a reasonable strategy for CA-LANPC with favorable tumor response after NAC.