Testicular cancer risk among young men: role of cryptorchidism and inguinal hernia.

The role of cryptorchidism (undescended testis) and inguinal hernia in the etiology of testicular cancer among men aged 18-42 years was evaluated in a case-control study of 271 cases and 259 controls referred to three collaborating medical centers in the Washington, DC, area. The relative risk of testicular cancer for men who reported a history of an undescended testis was 3.7 (95% confidence interval = 1.6-8.6). The risk increased with increasing age at correction; the risk was highest for those men whose cryptorchid testis was never corrected. Among unilateral cryptorchids, no increased risk of testicular cancer was observed for the normally descended testis. There was only a slight excess risk for men without cryptorchidism who had a herniorrhaphy; however, those who underwent a hernia operation after age 7 had a significantly elevated risk of testicular cancer on the same side as the hernia. This case-control study is the first one to support the clinical recommendations for early surgical correction of cryptorchidism and inguinal hernia. Data from this study suggest that the excess cancer risk associated with cryptorchidism is due to internal factors that affect the undescended testis rather than to some underlying developmental abnormality.