Men with a history of infertility have a markedly increased risk of subsequently developing testicular cancer.
The study was based on data from the largest cohort of infertility patients to date, involving more than 51,000 couples who were evaluated for in-fertility at 15 treatment centers in California between 1965 and 1998.
"It is no mystery that there has been a dramatic and continued rise in testicular germ-cell cancers in U.S. men over several decades," said principal investigator Thomas J. Walsh, MD, clinical instructor in urology working with Paul Turek, MD, and colleagues. "While it is more difficult to prove, it appears that there has been a simultaneous decline in semen quality and fertility. We wondered whether these trends could be connected."
"But evidence from Danish cohorts may not be generalizable to U.S. men, and data from U.S. studies are limited and discrepant," Dr. Walsh cautioned.
These records were compared with information from the California Cancer Registry, which included data for 10 regions in the Surveillance, Epidemiology, and End Results program for the period 1988 to 2004. Men whose cancer diagnosis preceded that of infertility were excluded.
Investigators identified all cases of histologically confirmed testicular germ-cell cancers occurring at least 1 year after infertility evaluation (to address reverse causality) in men evaluated for infertility from 1987 to 1998. Information on testis cancer stage, histology, and cryptorchidism was collected. The standardized incidence ratio (SIR), which is the number of observed cases of cancer divided by the expected cases, was used to determine possible associations between infertility and testis cancer.
Among the cohort of 42,283 male partners in infertile couples, 44 cases of post-infertility testicular cancer were identified. This figure was much higher than the number of expected cases-26-yielding an SIR of 1.7. The age-stratified SIR showed a strong association between male factor infertility and the development of testis cancer, especially in men 30 to 34 years old. In those men, the SIR was 2.5, based on the nine cancers observed among 545 men and compared to the expected four cases, Dr. Walsh reported.