Objectives: The objective of this study is to evaluate long-term outcomes, specifically patterns of tumor recurrence, in patients with adult medulloblastoma treated with radiotherapy.
Methods: We recorded outcomes of 28 (median age, 25 y) patients 18 years old or above with M0 to M3 medulloblastoma treated between 1971 and 2012. Among them, 61% had standard-risk disease. All received craniospinal irradiation with a posterior fossa boost. Median dose to the craniospinal axis was 36 Gy. Median total dose to the primary site was 55.9 Gy and 46% received chemotherapy.
Results: Median follow-up among survivors was 14.2 years. At 5 and 10 years, local control was 80% and 73%, overall survival was 71% and 59%, cause-specific survival was 71% and 63%, and freedom from progression was 68% and 59%. Tumors recurred in 11 patients (39%); median time to recurrence was 2.4 years, and 82% of recurrences developed in patients with standard-risk disease. Of the recurrences, 55% involved the primary site; 36% were bone metastases without neural axis recurrence. There were no isolated recurrences in the spinal canal or ventricular system outside of the posterior fossa.
Conclusion: The primary site is the main site of medulloblastoma recurrence, with isolated bone metastases more common in adults than children. Our results prompt us to consider 4 modifications to our treatment approach with adults who present with medulloblastoma: (1) initial staging to include PET or bone scan; (2) radiotherapy dose to the primary site of 59.4 Gy; (3) chemotherapy during and/or following radiotherapy in medically fit patients; (4) follow-up to include PET or bone scan twice a year for 3 years.