Medulloblastoma is extremely rare in adults. The role of chemotherapy for average-risk adult patients remains controversial. Surgery and radiotherapy provide a significant disease control and a good prognosis, but about 25% of average-risk patients have a relapse and die because of disease progression. No data in average-risk adult patients are available to compareradiotherapy alone and radiotherapyfollowed byadjuvant chemotherapy.

We analyzed 48 average-risk patients according to Chang classification diagnosed from 1988 to 2016.

Median age was 29 years (range 16-61). Based on histological subtypes, 15 patients (31.3%) had classic, 15 patients (31.3%) had desmoplastic, 5 patients (10.4%) had extensive nodularity and 2 patients (4.2%) had large cells/anaplastic medulloblastoma. Twenty-four patients (50%) received adjuvant radiotherapy alone and 24 (50%) received radiotherapy and chemotherapy. After a median follow-up of 12.5 years, we found that chemotherapyincreases progression-free survival (PFS-15 82.3 ± 8.0% in patients treated with radiotherapy and chemotherapyvs. 38.5% ± 13.0% in patients treated with radiotherapy alone p = 0.05) and overall survival (OS-15 89.3% ± 7.2% vs. 52.0% ± 13.1%, p = 0.02). Among patients receiving chemotherapy, the reported grade ≥ 3 adverse events were: 9 cases of neutropenia (6 cases of G3 neutropenia [25%] and 3 cases of G4 neutropenia [13%]), 1 case of G3 thrombocytopenia (4%) and 2 cases of G3 nausea (8%).

Our study with a long follow up period suggests that adding adjuvant chemotherapy to radiotherapy might improve PFS and OS in average-risk adult medulloblastoma patients.