Impact of radiation response on survival in pediatric medulloblastoma with residual or disseminated disease.

Background: This study aimed to determine the clinical impact of radiation response on survival in patients with medulloblastoma (MB) and to explore the predictive factor of radiation response.

Methods: Data from 170 pediatric patients with MB and residual disease or metastasis before radiotherapy (RT) were analyzed.

Results: The median follow-up period was 5.2 years. A total of 74 (43.5%) patients achieved CR, 85 (50.0%) patients achieved PR, 8 (4.7%) patients had SD, and 3 (1.8%) patients developed PD after RT. The five-year post-RT progression-free (prtPFS) and overall survival (prtOS) were superior in patients who achieved CR compared to those who did not (prtPFS: 67% ± 6% vs. 42% ± 6%, P < 0.001; prtOS: 82% ± 5% vs. 44% ± 6%, P < 0.001). Multivariable logistic regression analysis showed that residual disease site was the predictive factor for radiation response, patients who had residual disease in both the brain and spinal cord before RT had higher non-CR rate (OR: 7.312, 95%CI 3.375-15.845, P < 0.001). Multivariate Cox analysis revealed that radiation response and large cell/anaplastic subtype were independent prognostic factors for survival (P < 0.05).

Conclusions: Radiation response was an independent prognostic factor for survival in patients with MB. Patients who did not achieve CR after RT should receive intensified adjuvant chemotherapy to improve survival.