MBCL-31. TREATMENT RESULTS AMONG 106 PATIENTS WITH MEDULLOBLASTOMA OF MOLECULAR SUBGROUP 3

OBJECTIVE: To evaluate the treatment results among 106 patients of molecular subgroup 3 and to determine the factors affecting the prognosis. PATIENTS AND METHODS: In all the patients, initial removal of the tumor was performed. All the patients got chemoradiotherapy according to the HIT protocol. There were 34girls and 72boys. Most patients were over 3 years:74 compared to 32 younger than 3. The majority of the patients had stage M+: 65; in 38 stage M0 was determined; in 3patients, stage was not specified, Mx.MYC amplification was found in 20 patients; MYCN amplification, in 4 patients. Classic medulloblastoma was predominant: 65, and 41 patients had anaplastic/large cell medulloblastoma. RESULTS: The five-year progression-free survival was 0.51±0.05, the five-year overall survival was 0.52±0.04.The median survival was 82months,and the median progression-free survival was 37 months. There were no significant variations of PFS depending on the sex and age. The treatment results depended on the histological subtype: for classic medulloblastoma, the five-year PFS was 0.57; for the anaplastic/largecell,0.38(р = 0.02030). The presence of metastases significantly affected the survival: PFS for stage M0 was 0.77; for stage М+,0.35(р = 0.00062). Patients with MYC amplification had a significantly worse survival compared to MYCN patients and those without MYC amplification: 0.1, 0.75, and 0.58, respectively (р = 0.00002). Three patients with MYC amplification are alive: two patients had MGMT methylation detected. CONCLUSIONS: The results of treatment among the patients with molecular subgroup 3 depended on the tumor subtype, presence of metastases, MYC amplification and MGMT methylation. In the absence of unfavorable factors, the survival was the same as in molecular subgroup 4.