Impact of salvage treatment for recurrent medulloblastoma in previously irradiated patients (KROG 23-02): A multi-institutional retrospective study.

Background: Despite intensified frontline therapy for medulloblastoma, 20-30% of patients still experience disease failure. Outcomes for recurrent disease remain poor, largely due to the lack of standardized salvage strategies. This study evaluated treatment patterns and outcomes of salvage therapy in recurrent or progressive medulloblastoma. Methods: Patients aged ≤ 21 years with histologically confirmed medulloblastoma diagnosed between 2000 and 2020 were analyzed. Inclusion criteria required prior surgery or biopsy followed by postoperative radiotherapy and completion of initial therapy. Disease recurrence or progression was confirmed by MRI and clinical assessment. Local control treatment (LCT) was defined as salvage radiotherapy or surgery. Primary endpoints were progression-free survival (PFS) and overall survival (OS) from initial recurrence. Results: Seventy-six patients from five centers were included. The median time to first failure was 23.9 months (IQR, 14.9-36.2). Salvage treatments included chemotherapy alone (n = 26), LCT alone (n = 11), and combined LCT and chemotherapy (n = 30); 9 patients received best supportive care. The 1- and 3-year PFS rates were 47.4% and 7.2%, while OS rates were 81.1% and 42.8%, respectively. In univariate analysis, MYCN non-amplification, chemotherapy, and LCT were associated with improved PFS. In multivariate analysis, both chemotherapy (HR, 0.39; p = 0.003) and LCT (HR, 0.51; p = 0.013) remained significant prognostic factors for PFS. For OS, focal relapse and chemotherapy were associated with improved survival. Conclusions: Outcomes for recurrent medulloblastoma remain unfavorable. However, LCT was associated with improved PFS, while chemotherapy was associated with both improved PFS and OS.