Second cancer following cancer of the male genital system in Denmark, 1943-80.

The incidence of second primary cancers was investigated among 19,886 patients with prostate cancer. The analysis disclosed 594 new cancers, which was significantly less than the expected 1,176 cases (relative risk = 0.51). Deficits were observed for most sites but were only significant for cancers of the lip, lung, and gastrointestinal organs. The average age at diagnosis of prostate cancer was 72 years. It is likely that the apparent deficit in the incidence of second neoplasms resulted from less diagnostic aggressiveness in elderly patients with cancer compared with younger patients. The risk of developing a second primary cancer was also investigated in 4,290 men with testis cancer reported to the Danish Cancer Registry between 1943 and 1980. A significant 29% excess of second cancers was found (174 observed vs. 135 expected). A bimodal distribution of risk over time was found with a 67% excess seen among patients followed for 1-4 years that was mainly due to increased incidence of acute nonlymphocytic leukemia and malignant lymphomas. Among patients surviving 10 or more years, the overall excess of 32% observed was mainly due to cancers of the gastrointestinal tract and the urinary bladder. As part of the initial treatment for testis cancer, 82% of the patients received radiotherapy. Chemotherapy was rarely given before 1975 and then mostly to patients with a poor prognosis. Late effects of radiotherapy conceivably could account for some of the excess of second hematologic as well as solid neoplasms.