Local control in non-metastatic medulloblastoma

A single-institution review of long-term outcomes and factors affecting local control (LC) following radiotherapy for non-metastatic medulloblastoma.

From 1963 to 2008, 50 children (median age, 7.3 years; range 1.2-18.5) with stage M0 medulloblastoma were treated with radiotherapy; half underwent a gross total resection (no visible residual tumor) or near-total resection (< 1.5 cm(3) of gross disease remaining after resection). Median craniospinal dose was 28.8 Gy (range 21.8-38.4 Gy). Median total dose to the posterior fossa was 54.3 Gy (range 42.4-64.8 Gy). Eighteen patients (36%) received chemotherapy as part of multimodality management, including 11 who received concurrent chemotherapy.

Median follow-up was 15.7 years (range 0.3-44.4 years) for all patients and 26.6 years (range 7.3-44.4 years) for living patients. The 10-year overall survival, cancer-specific survival, and progression-free survival rates were 65%, 65%, and 69%. The 10-year LC rate was 84% and did not significantly change across eras. Four percent of patients experienced local progression five years after treatment. On univariate analysis, chemotherapy and overall duration of radiotherapy ≤ 45 days were associated with improved LC. Patients receiving chemotherapy had a 10-year 100% LC rate versus 76% in patients not receiving chemotherapy (p = 0.0454). When overall radiotherapy treatment lasted ≤ 45 days, patients experienced a superior 95% 10-year LC rate (vs. 73% in patients treated > 45 days; p = 0.0419). Three patients (6%) died from treatment complications, including radionecrosis/cerebellar degeneration, severe cerebral edema leading to herniation, and secondary malignancy.

While we cannot draw definitive conclusions given the retrospective nature of our study, our long-term data suggest that reductions in craniospinal dose and boost target volume to reduce toxicity have not compromised disease control in the modern era. Our data also support analyses that implicate duration of radiotherapy, rather than interval between surgery and radiotherapy, as a factor in LC. Chemotherapy in multimodality management of medulloblastoma may have an underappreciated role in improving LC rates.