Breast cancer risk in mothers of children with osteosarcoma and chondrosarcoma.

Mothers of a population-based series of 86 children with osteosarcoma or chondrosarcoma were traced and their health status or cause of death ascertained. There were 6 cases of breast cancer among these mothers and 6 other cancers. Risk of breast cancer was approximately three times that expected, and appeared to be highest in mothers of boys and in mothers of children under the median age at diagnosis. The mothers who developed breast cancer were relatively young at diagnosis compared with population data. Risk of other malignancies in the mothers was not in excess of expectation. These findings are in line with those reported for breast cancer risk in mothers of children with soft tissue sarcomas, and provide further indications of a genetic component in the aetiology of these cancers.