Second primary malignancy after Hodgkin's disease, ovarian cancer and cancer of the testis: a population-based cohort study.

The risk of second primary malignancy was assessed in a population-based cohort study of all persons registered with Hodgkin's disease (n = 2,970), ovarian cancer (n = 11,802) and testicular cancer (n = 2,013) in the South Thames Cancer Registry during the period 1961-80, to identify for further study those second malignancies which might be treatment-related. A total of 244 second malignancies was observed. After adjustment for age, sex and calendar period, the relative risk of any second malignancy was 1.4 (90% confidence interval (CI) 1.1-1.7) after Hodgkin's disease, 1.1 (90% CI 1.0-1.2) after ovarian cancer and 0.7 (90% CI 0.5-1.0) after testicular cancer. In particular, the relative risk for leukaemia was 11.9 after Hodgkin's disease, 3.7 after ovarian cancer and 2.5 after testicular cancer. Excess risks were also observed for cancers of the cervix and lung after Hodgkin's disease, for cancers of the breast, lung and rectum after ovarian cancer, and for contralateral testicular cancer. Confounding by social class or smoking does not explain these observations. The excess risks of leukaemia and of second cancer were higher in patients first diagnosed with Hodgkin's disease and ovarian cancer in the 1970s than for those first diagnosed in the 1960s. Increased use of multiple-agent chemotherapy regimes for these tumours in the 1970s may have contributed to these increases in excess risk.