A case-control study of leukaemia as a second primary malignancy following ovarian and breast neoplasms.

The National Cancer Registry of the German Democratic Republic identified 105 leukaemias which had developed during 1968-1980 as second primary malignancies in women previously registered with a tumour of the breast or ovary. Matched controls were selected who had been diagnosed with the same first tumour, but had survived without further malignancy as long as the corresponding case. Treatment records were abstracted for leukaemia cases and controls, and a comparison made of the therapy received. There was a ten-fold increase in the risk of leukaemia following ovarian cancer among those treated with chemotherapy, which was almost exclusively cyclophosphamide. Among the breast cancer survivors, the relative risk of acute leukaemia associated with cyclophosphamide was 2.7.