Sex-specific familial risks of urinary bladder cancer and associated neoplasms in Sweden.

Male gender and a family history of cancer are established risk factors for urinary bladder neoplasms. This study used the latest update of the Swedish Family-Cancer Database, which includes 42,255 bladder cancer patients, to investigate the sex-specific incidences and types of tumors in relatives of bladder cancer patients. Men with parents or siblings affected by lung cancer did not show an increased risk of bladder neoplasms. Among women, the familial association was restricted to daughters of women with lung cancer. Brothers showed higher risks than the sons of bladder cancer patients. Men older than 54 years were at an increased risk of bladder cancer only if their fathers or siblings were diagnosed after age 65 years. The present data indicated a limited contribution of smoking to the familial clustering of bladder cancer with other neoplasms. The dependence of the relative risks on the type of familial relationship probably reflected a heterogeneous character of familial aggregation. Age-specific results suggested differential risk factors for tumors diagnosed before 50 years of age versus neoplasms detected later in life. The present data may guide the design of forthcoming gene identification studies and the interpretation of the genome-wide association studies that are about to be published.