The testicles are located inside the scrotum (a sac of loose skin that lies directly under the penis). Testicular cancer-also called germ cell cancer-occurs in the tissues of one or both testicles. Testicular cancers are relatively rare but highly curable, and occur predominantly in young and middle-aged males. The incidence of testicular cancer has been increasing in many western countries. Between 1975 and 2002, the rate of testicular cancer doubled in the United States.
The cause of testicular cancer is poorly understood. Developed countries have a higher prevalence of the disease than undeveloped countries, which suggests that environmental factors may be involved. An increased incidence of testicular cancer has been associated with early puberty, testicular trauma, cigarette and marijuana smoking, and exposure to toxic substances such as lead.
Researchers from the University of California at San Francisco studied data from 51,461 couples who were evaluated for infertility from 1967 to 1998 at 15 California infertility centers. They then linked data from 22,562 male partners to the California Cancer Registry and compared the incidence of testicular cancer in this cohort with incidence in an age-matched sample of men using the Surveillance Epidemiology and End Results (SEER) database.
The results indicated that the men who sought infertility treatment had an increased risk of developing testicular cancer and that men with known male factor infertility were 2.8 times more likely to develop testicular cancer than those without infertility. In total, the researchers identified 34 cases of testicular cancer among men in the infertility cohort.
The researchers concluded that “men with male factor infertility have an increased risk of subsequently developing testicular cancer, suggesting the existence of common etiologic factors for infertility and testicular cancer.”