Familial testicular cancer: report of six cases and review of the literature.

The cause of testicular cancer, like most other cancers, is unknown. Certain risk factors such as cryptorchidism, carcinoma in situ, and a preceding contralateral testicular germ cell neoplasm are known to predispose a person to the subsequent development of a testicular malignant lesion. Familial testicular cancer has been debated as a potential and possibly independent risk factor. Evidence in favor of such a hypothesis, based on various genetic studies reported during the past few decades, is reviewed. We add to the existing literature our experience with six cases of familial testicular cancer encountered during a 10-year period, consisting of four father-and-son pairs, one pair of nontwin brothers, and a 23-year-old man who had a maternal uncle with a history of testicular cancer.