Second cancer following cancer of the male genital system in Connecticut, 1935-82.

The risk of a second primary cancer developing was evaluated in nearly 20,000 men with cancers of the prostate or testis in Connecticut, 1935-82. Among 18,135 men with prostate cancer, a significant 15% deficit of all second cancers was observed [1,053 vs. 1,241; relative risk (RR) = 0.85; 95% CI = 0.80-0.90], most notably for respiratory (RR = 0.7) and digestive cancers (RR = 0.8). The absence of a colon cancer risk lends little support to the idea of common risk factors such as dietary fat consumption. Only the risk for salivary gland cancer was significantly increased, possibly due to chance. Leukemia was significantly elevated among men observed for 10 and more years (RR = 2.2). In contrast to most other index tumors, the prostate stands out as being associated with an overall low risk of second cancer development. The reasons for these deficiencies have not been explained. Among 1,446 men with testis cancer, a significant twofold risk of second cancers was seen (104 vs. 50.1). A fivefold risk of leukemia (8 vs. 1.5) was not related to treatment or age. Contralateral testis cancer (6 vs. 0.5) was elevated in men treated with and without radiation. Risks for kidney cancer (5 vs. 1.5), bladder cancer (9 vs. 3.4), pancreatic cancer (6 vs. 1.5), non-Hodgkin's lymphoma (6 vs. 1.5), and prostate cancer (12 vs. 5.9) were significantly increased. No trends over time were noted for any cancer. Overall risk of second cancer development tended to be higher in younger men with testis cancer. The relationship of leukemia to testis and prostate cancers should be investigated in future research.