Medulloblastoma: Radiotherapy Result with Emphasis on Radiation Dose and Methods of Craniospinal Treatiment

Kim, Il Han; Ha, Sung Whan; Park, Charn Il; Cho, Byung Kyu

Abstract

Twenty five patients with histologically proven medulloblastoma received craniospinal radiotherapy (CSRT) at the Seoul National University Hospital from 1979 to 1984. The extent of tumor removal was biopsy only in 2 patients, partial in 18, and near total in 5. With orthogonal technique of CSRT, mainly 55 gy was delivered to the posterior fossa(PF). 40gy to whole brain (WB), and 30 gy to whole spine (WS). And with AP : PA technique, 50 gy to PF, 45-50 gy to WB, and 36 gy to WS. Complete remission was obtained in 84% of patients. Among 21 CR's 10 failures were observed, thus total failure rate was 56% (14/25). Of 14 failure 13 had the primary failure, 11 failed in primary site alone, 1 failure was combined with ventricular seeding, and another 1 was combined with neck node metastasis. There was 1 isolated spinal failure. Actuarial overall survival rates at 3 and 5 years were 75% and 54%, and disease-free survival rates were 58% and 36%, respectively. Better 5 year disease-free survival was noted in patients with 55gy to the posterior fossa than those with 50 gy (62% vs 17%, p<0.05), in patients treated with orthogonal technique than those treated with AP : PA technique (87% vs 12%, p<0.05), and in patients with near total removal than those with partial or less removal of tumor (56% vs 30%, N.S.) Re-irradiation was not satisfactory. No severe late sequelae was notede among the survivors. For the higher control of medulloblastoma, dose to posterior fossa should be at least 55 gy with orthogonal CSRT to small tumor burden. And dose reduction in the subarachnoidal space might be safe, but optimal dose to the subarchnoidal space should be determined by the thorough tumor staging before radiotherapy