Cryptorchidism (or undescended testis) can increase the risk of developing cancer in the affected testis, as well as the opposite testis, even if it is normally descended. The degree to which surgical correction of cryptorchidism (called "orchidopexy") can decrease this risk has not been determined, although there appears to be a protective effect when surgery is performed prior to puberty.
Individuals who have had testis cancer in one testis have about a 3-4% chance of developing cancer in the opposite testis. All individuals who have a history of cryptorchidism or testis cancer require lifelong surveillance by examination. White men versus Black and Asian men have a four- to five-times higher risk for developing testis cancer. Evidence for other risk factors has been lacking. Although patients often report a history of preceding testicular trauma, this event usually leads to self-examination and incidental discovery of a mass that is not associated with the trauma.
HIV patients have a greater risk of developing other tumors such as lymphoma and sarcoma that can affect the testes; however, these patients' risk of GCT appears to be the same as seen in the overall population.
Patients with Klinefelter's syndrome are at greater risk of forming GCT outside of the testes, notably inside the chest (mediastinum). Exposure of pregnant women to diethylstilbesterol (DES) appears to increase the incidence of testis cancer in their male children. However, the effect of DES on adult men does not appear to increase the risk of developing testis cancer.
Some have proposed that increased scrotal temperature, which may occur in those with a sedentary lifestyle, may be a putative factor in the formation of testicular neoplasia. Investigations thus far are inconclusive.