Testicular cancer after vasectomy: origin from carcinoma in situ of the testis.

Vasectomy is a commonly used male contraceptive procedure. Reports have indicated that vasectomy is associated with an increased risk of development of germinal testicular cancer. Carcinoma in situ of the testis (CIS) is a preinvasive lesion which precedes germinal testicular cancer. CIS is almost always found in the tissue adjacent to a germinal testicular cancer. It is believed that CIS is a malignant gonocyte formed during embryogenesis. We have studied the testicular tissue from 5 previously vasectomised patients with testicular cancer and found CIS in the tissue adjacent to their cancer as well as changes in the epididymis of the patients. We discuss the findings and conclude that testicular cancers occurring after vasectomy is not an exception from the rule that testicular cancer originates from CIS. Thus, there is no causal relationship between vasectomy and testicular cancer, but vasectomy might precipitate the development of testicular cancer from the preinvasive CIS lesion.