Mortality and cancer incidence following radiotherapy for seminoma of the testis.

From the records of the Thames Cancer Registry, 859 patients were identified, who were treated with radiotherapy for seminoma of the testis between 1961 and 1985. Second cancer incidence and mortality and also causes of non-cancer deaths in the study population were examined. Fifty-one (6%) patients died of testicular cancer, 42 within 5 years of diagnosis. There were 42 second cancers (other than second testicular cancers), and 20 deaths from second cancer (expected, 22.1--non-significant). The only subtype of cancer with a notable excess was leukaemia (4 incident cases observed; 0.64 expected; relative risk 6.2, 95% C.I., 2.7-14.8, 95% C.I., 2.7-14.7). The overall death rate from causes other than testicular cancer was not elevated (82 observed, 82.06 expected). There was some suggestion of an increase in the risk of mortality with time; for 10 or more years after treatment the relative risk was 1.31 (95% C.I., 0.95-1.81). There was no evidence of excess non-cancer deaths (62 observed, 60 expected). We conclude that there is no definite evidence from this investigation of increased risk of mortality secondary to radiotherapy; however, the excess incidence of leukaemia may be treatment-related and the cohort will be followed further.