Description of the Evidence
Testicular cancer is more than four times more common among white men than black men,[8,9] with intermediate incidence rates for Hispanics, American Indians, and Asians. High-risk groups exist. Males with cryptorchidism have 3 to 17 times the average risk. Approximately 7% to 10% of patients with testicular tumors have a history of cryptorchidism.[7,8] Although the association is established, the biological mechanism underlying the association remains uncertain; testicular cancer and cryptorchidism may share environmental and/or genetic risk factors; or, it is the ectopic position per se that is a postnatal risk factor for testicular cancer, or it is a combination of the two. Orchiopexy may not prevent cancer in these children but allows clinical surveillance of patients with a previously impalpable gonad.
There is also an increased risk in males with gonadal dysgenesis and Klinefelter syndrome. Men with a family history of testicular cancer may be at a higher risk of this disease. A history of testicular cancer is associated with a higher risk of a contralateral tumor.[7,8] Although not consistently found, infertility, testicular atrophy, twinship, or abnormal semen parameters have been associated with a higher risk of testicular cancer, but the evidence is weak.[7,12,13,14]
There is a low cumulative risk of metachronous contralateral testicular cancer and a favorable overall survival of patients diagnosed with metachronous contralateral testicular cancer. Future research is necessary to delineate the genetic and environmental risk factors for testicular cancer.
An additional risk factor for the development of testicular cancer is the presence of carcinoma in situ (CIS), also called intratubular germ cell neoplasia. Testicular CIS appears to develop from fetal gonocytes and is characterized histologically by seminiferous tubules containing only Sertoli cells and malignant-appearing germ cells.
Early reports suggest that CIS is associated with the development of contralateral testicular cancer in 50% of patients at 5 years of follow-up. CIS will be found in approximately 5% of contralateral testes (approximately the same rate as cryptorchid testes).