Second primary tumours among survivors of childhood cancer treated with anticancer drugs.

Increasing attention is being given to the occurrence of second primary tumours among survivors of childhood cancer. Our aims are to examine the risk of a subsequent primary, particularly in relation to chemotherapy, in a well-defined cohort; and to examine interesting associations between first and second primary tumours in relation to therapy generally and chemotherapy in particular among a less well-defined group of cases developing at least two primary tumours. There is suggestive evidence from our data that chemotherapy is involved either directly or indirectly in the development of secondary leukaemia, and this confirms previous work. Our data, although based on small numbers, indicate consistent evidence of an association between cyclophosphamide and an increased risk of a second primary tumour following retinoblastoma; this may be due to cyclophosphamide, radiotherapy or an interaction between the two. Two cases of uterine cancer were observed among three patients given oestrogen replacement therapy.