Familial patterns of testicular cancer.

To date only 6 cases of testicular cancer have occurred in father-and-son pairs, 7 cases in monozygotic twins, and 11 in nontwin siblings. Of particular interest in reviewing these and other reports of cancer in family members are the age of onset of the cancer and the concordance of cell types among the variously related family members affected. We report a case of familial testicular cancer occurring in a patient, summarize known or suggested epidemiologic factors, and present a literature review of familial occurrences of testicular cancer.