Boost Gamma Knife Radiosurgery During Multimodality Management of Medulloblastoma/PNET Tumors

Abstract

Medulloblastoma/primitive neuroectodermal tumors (PNETs) are the most common malignant tumors of the central nervous system in children accounting for at least 20% of all childhood brain tumors (Kleihues and Cavenee (eds) Pathology and genetics of tumours of the nervous system. International Agency for Research on Cancer, Lyon, 2000). Multimodal treatment, including maximal feasible resection, fractionated neuraxis radiation therapy, and systemic chemotherapy is considered the standard initial strategy against these tumors. In spite of this, local and metastatic recurrences occur in 30–40% of patients, and such recurrences portend a poor prognosis for survival (Kleihues and Cavenee (eds) Pathology and genetics of tumours of the nervous system. International Agency for Research on Cancer, Lyon, 2000).

Stereotactic radiosurgery has been proposed as a potentially effective adjunctive therapy in the management of recurrent or residual medulloblastoma (as reported by Patrice, Tarbell, Goumnerova, Shrieve, Black, and Loeffler, Pediatr Neurosurg 22:197–203, 2005). At the University of Pittsburgh, Gamma Knife stereotactic radiosurgery (GKRS) was used in the treatment of 7 pediatric and 12 adult patients who underwent a total of 36 procedures for residual, locally recurrent and metastatic medulloblastoma/PNET tumors. GKRS was administered to pediatric patients who failed initial multimodal treatment. The procedure was well tolerated and none of the patients experienced adverse radiation effects. Local tumor control was more likely in patients with smaller irradiated tumor volumes. Ultima-tely, delayed local progression, distant relapse, or leptomeningeal seeding led to the death of all pediatric patients in our series. Further efforts to develop more effective strategies are needed for this patient population.