Hypofractionated stereotactic radiotherapy in the management of recurrent or residual medulloblastoma/PNET

Abstract

To evaluate the efficacy and toxicity of hypofractionated stereotactic radiotherapy in the management of locally recurrent or residual central nervous system (CNS) primitive neuroectodermal tumors (PNETs). Between 1991 and 2005, 12 patients with locally recurrent medulloblastoma and two patients with residual supratentorial PNET were treated with hypofractionated stereotactic conformal radiotherapy (SCRT). Nine patients were treated for first recurrence, two patients after the 2nd, and one patient after 3rd recurrence. Median age at diagnosis was 20 years (range: 4-35 years) and median age at SCRT 25 years (range: 7-41 years). Nine of 12 patients underwent resection at recurrence and 13 patients received at least one cycle of chemotherapy prior to SCRT. All received focal SCRT (30-40 Gy/6-8 #) using non-coplanar arcs (n = 6) or fixed conformal non-coplanar fields (n = 8). Median overall survival was 29 months (95% CI: 6-51 months) and median progression-free survival was 12 months (95% CI: 5-19 months). Local progression-free survival at 1 and 3 years was 80% (95% CI: 55-100%) and 48% (95% CI: 11-85%). Causes of death were recurrent CNS disease (n = 7), herpes encephalitis (n = 1), and metastatic PNET outside the CNS (n = 1). Hypofractionated SCRT provides effective local control with acceptable toxicity for patients with recurrent localized PNET. However, overall long-term disease control is rare and limited by the occurrence of CSF mediated relapses, which thus could benefit from intensive systemic chemotherapy as part of the primary relapse strategy even in local recurrences. Larger multi-national studies will be necessary to assess the value of such combined treatment approaches.