[Second malignant neoplasms in childhood].

Sixty-six cases of multiple primary neoplasms in children in Japan were collected, including 8 cases of our own. These could be divided into 19 synchronous and 47 metachronous multiple neoplasms. Metachronous or multiple primary neoplasms comprised leukemia, osteosarcoma, mesenchymal sarcoma, epithelial carcinoma and others in contrast to synchronous neoplasms which consisted of many pairs of embryonic tumors. The presumptive factors for multiple primary neoplasms suggested radiotherapy-associated cancers in 30%, radiochemotherapy-associated in 13%, chemotherapy-associated in 34%, and genetic factor-related in 36% of cases. Chromosomal analysis was performed in 12 cases. Three of 4 leukemias revealed major karyotypic abnormalities in the leukemic cells. No 13q14, deletion was detected in 5 cases with multiple primary neoplasms developed with retinoblastoma. Frequent incidence of sister chromatid exchange (SCE) was detected in cultured fibroblasts or lymphocytes from one of 3 cases of second primary neoplasms associated with chemotherapy. The time interval between both neoplasms ranged from 2 to 15 years in the majority of cases. Chemotherapy-associated multiple primary neoplasms seemed to appear more quickly than radiotherapy-associated multiple primary neoplasms. Seven children out of 459 long-term survivors of childhood cancer developed multiple primary neoplasms during the period from 5 to 20 years after diagnosis of the first tumor at the National Cancer Center Hospital, Tokyo. The relative risk was suggested to be 14 times higher than the expected incidence of childhood cancer in Japan. Refinement of treatment, long-term monitoring and protective procedures for high-risk patients against multiple primary neoplasms are therefore warranted.