10193- BT-8 4 CASES OF SECONDARY CANCER AFTER TREATMENT FOR PEDIATRIC MEDULLOBLASTOMA

Abstract INTRODUCTION The number of long-term survivors of medulloblastoma has increased due to advances in treatment, the occurrence of secondary neoplasms has become a new problem. We report four secondary neoplasms after medulloblastoma treatment. PATIENTS Of the 26 cases of pediatric cerebellar medulloblastomas that have undergone initial treatment in our department, four have developed secondary neoplasms. The ages of the patients who developed secondary cancers ranged from 17 to 48 years (mean 30 years), with two men and two women, and the ages ranged from 6 to 33 years (mean 21 years) after initial treatment. Two infratentorial glioblastomas, one DIPG, and one multiple meningiomas occurred. The radiation doses at the tumor site were 50.4 and 55.2 Gy for the cases of glioblastoma, 49.6 Gy for the case of DIGP, and 20.5 Gy for the case of multiple meningiomas. RESULTS The two patients with cerebellar glioblastoma underwent treatment, but they had dissemination from the time of onset and died 10 and 12 months after onset. The patient with multiple meningiomas underwent tumor resection and has maintained an independent social life. The patient with DIPG is currently undergoing detailed examination. DISCUSSION Secondary neoplasms occurred in 4 of 26 cases (15%) in our overall study, but the incidence rate increased to 2 cases (50%) in 4 long-term survivors who survived for more than 30 years after treatment for pediatric medulloblastomas. The incidence of secondary neoplasms increases over time if the latency period exceeds 10 years, and radiation exposure at a young age in particular is considered to be a risk factor for secondary cancer. It is also said that the incidence of secondary cancers increases in proportion to the radiation dose, but it is necessary to comprehensively evaluate the occurrence of secondary neoplasms, including not only the radiation dose but also chemotherapy, genetic predisposition.