Reappraisal of clinical outcome in adult medulloblastomas with emphasis on patterns of relapse

Background. Clinical outcome and prognostic factors were assessed in adult medulloblastoma patients, with emphasis on patterns of relapse. Patients and methods. Records of 36 consecutive adult patients with medulloblastoma were reviewed. Patients were classified into 2 prognostic groups according to the extent of disease and quality of surgical excision based on the early postoperative magnetic resonance imaging (MRI) findings. Standard-risk (SR) patients (n = 11) received postoperative craniospinal radiation therapy (RT) only, 36 Gy, 1.8 Gy per daily fraction, with a 18 Gy boost to the posterior cerebral fossa (PCF). High-risk (HR) patients (n = 25) received additional adjuvant chemotherapy. Results. With a median follow-up of 46 months (range 5-155), 19 patients experienced tumour relapse. Sites of relapse(s) included tumour bed in 6 patients, resulting in a PCF control of 83.4%. Three-year overall survival (OS) and progression-free survival (PFS) were 67.3% and 57.4%, respectively. The comparison of the HR and SR populations demonstrated significant differences in OS (p = 0.005) and PFS (p = 0.001). Quality of surgical excision and extent of disease beyond the PCF were predictive factors for OS (p = 0.04, p = 0.001, respectively) and PFS (p = 0.004, and p = 0.02, respectively). Conclusion. The quality of resection was a significant prognostic factor, suggesting that surgery should be as extensive as possible. Systematic postoperative MRI allowed accurate selection of SR patients for whom RT alone was enough to obtain high local control. Every effort should be made to avoid RT disruption. Increased delay led to worse outcome.