NEUROFIBROMATOSIS TYPE-1 AND CHILDHOOD-CANCER

Background. Patients with neurofibromatosis type 1 (NF1) are prone to develop malignancy, particularly malignant schwannoma and glioma in ad ults. Methods. To assess the risk for childhood malignancy in NF1, 26, 084 patients with cancer younger than 15 years of age registered from 1969 to 1989 in the Japan Children's Cancer Registry were reviewed. Th e incidence of NF1 in each type of cancer was compared with that in th e Japanese population. Results. Fifty-six children with cancer had NF1 in the national registry. The incidence of NF1 (0.21%) was 6.45 times that of the expected estimated rate of 1 per 3000 in the Japanese pop ulation. These tumors tended to be type and site specific. The NF1 inc idence was extremely high in optical nerve glioma (12.5%), other centr al nervous system gliomas (0.9%), and malignant schwannoma (31.4%). Fo r nonneural tumors, NF1 incidence was increased in rhabdomyosarcoma (1 .36%), particularly those in urogenital organs, and in myelogenous leu kemia (0.27%). Epithelial carcinomas were not observed in the group of patients with NF1. Conclusion. The risk for glioma and malignant schw annoma increases in children and adults with NF1. Moreover, the risk f or two childhood malignancies, myelogenous leukemia and rhabdomyosarco ma, increases in children with NF1. The NF1 gene seems to increase the risk not only for neural tumors but also for some nonneural tumors in an age-specific, organ-dependent pattern of carcinogenesis.