MEDULLOBLASTOMA IN VERY YOUNG-CHILDREN - OUTCOME OF DEFINITIVE CRANIOSPINAL IRRADIATION FOLLOWING INCOMPLETE RESPONSE TO CHEMOTHERAPY

Purpose: To evaluate survival and neurodevelopmental outcomes following radiation therapy in infants and young children with residual or progressive medulloblastoma after primary chemotherapy. Patients and Methods: Thirteen young patients (≤ 36 months old) with medulloblastoma were treated with preirradiation multiagent chemotherapy and maximal surgical resection. Patients were scheduled to receive radiation therapy at the time of documented disease progression or upon completion of chemotherapy with residual disease. All patients underwent neurodevelopmental evaluation at the time of diagnosis, before receiving radiation therapy, and at yearly intervals posttreatment. Results: Two patients completed the scheduled chemotherapy with residual disease and received delayed radiation therapy. The remaining 11 patients had either local or leptomeningeal progression during chemotherapy (median time to progression, 5 months). Six patients had a complete response (CR) to radiation therapy, and three of these children are alive 48 to 104 months postdiagnosis. Of the five patients who had progressive disease (PD) during radiation therapy or residual imaging abnormalities after treatment, only one is alive (with stable enhancing leptomeningeal abnormalities) 48 months postirradiation. Two additional survivors were rendered disease-free by surgical resection before radiation therapy and are without evidence of disease at 91 and 107 months after diagnosis. Thus, six of 13 patients are alive at 48 to 107 months postdiagnosis. Neurodevelopmental scores tended to be below age norms at diagnosis; scores improved during chemotherapy, but then decreased during posttreatment follow-up evaluation. Conclusion: Radiation therapy appears to produce long-term disease-free survival in a proportion of very young patients who have progressive or residual medulloblastoma during or after primary chemotherapy. However, neurodevelopmental deficits are frequent among long-term survivors.