Results of a multicenter study of the treatment of WNT medulloblastomas in children

Medulloblastomas of the WNT molecular group (MB-WNT) represent the smallest group of MB and account for only 10 % of the total. This molecular group is characterized by a favorable prognosis. Given the aggressive treatment regimens for MB, reducing the intensity of therapy for prognostically favorable tumors seems justified. Purpose of the study – to demonstrate the results of treatment of children with MB-WNT and to determine the impact on survival of various prognostic factors. The study included 85 patients with MB-WNT under the age of 18 who received treatment and were followed up from 1993 to 2022. Median age at diagnosis was 10 years (min – 3, max – 17). All patients had classical MB. Metastatic spread of the tumor at the time of diagnosis was detected in 18 (21.2 %) patients, the presence of a residual tumor according to postoperative magnetic resonance imaging – in 32 (37.7 %). Somatic mutations in the TP53 gene were detected in 10 (7.1 %) patients, in the CTNNB1 gene – in 79 (92.9 %), in the APC gene – in 5 (5.9 %), chromosome 6 monosomy – in 76 (89.4 %) children. At the time of the analysis, 74 (87.1 %) patients were alive, 11 (12.9 %) patients died, a relapse was diagnosed in 6 (7.1 %) patients, of which 5 died from disease progression, 1 patient is alive in the second remission. One patient in long-term remission developed secondary meningioma 20 years after the diagnosis of MB. The 10-year progression-free survival (PFS) was 0.92. 5-year overall survival (OS) was 0.90, 10-year – 0.86. The median OS is 112 months. When analyzing the sample of patients with MB-WNT in our study, PFS and OS were statistically significantly higher in girls without metastatic tumor spread, with total resection of the tumor, stratified into the low-risk group, and in the absence of a somatic mutation in the TP53 gene in the tumor tissue. In multivariate analysis, PFS was influenced by the stage of the disease and the presence of a somatic mutation in the TP53 gene in the tumor tissue; on OS – only the presence of a somatic mutation in the TP53 gene in the tumor tissue.