So what did we find?
The study showed that men who are infertile have a much higher risk (3 times) of developing testis cancer later in life than the average citizen. And this was based on some serious number crunching. We worked from a huge database of over 51,000 infertile couples who sought care over a 22 year period in California. The male partners were cross referenced with a California cancer registry to figure out who among them developed testis cancer as they got older. Among infertile couples in whom the male partner was not the reason for infertility, the future risk of testis cancer was the same as in the general population. However, among infertile men who were themselves the cause of the infertility, the risk of future testis cancer was 3 times higher.
So what does this really mean? Well, first of all, it confirms studies from Europe that have suggested the same thing is happening there. This confirmation in a U.S. based study is important, because the rate of testis cancer in many European countries is much higher than it is in the U.S. It also implies that there may be a connection of some kind between male infertility and testis cancer.
But what kind of connection could exist between male infertility and testis cancer? Well, environmental exposures might link these two conditions. However, the kinds of substances that could do this are still unclear. Estrogenic compounds such as bisphenol A, phthalates and pesticides have garnered much press lately as they alter sexual development in animals, but have not been definitively linked either to testis cancer or human infertility.
The connect, I think, may be even more basic: it probably involves genes and gene mutations. About 10 years ago, we and others reported that severely infertile men have more trouble than other men in properly repairing the daily breaks and kinks that occur in everyone’s DNA with daily use. Because faulty DNA repair is clearly associated with cancer in humans, this led us to surmise back then that infertile men with faulty DNA repair might have a higher risk of cancer later in life. And voila! The results from the recent research appear to support this idea.
For the time being, the risk holds only for testis cancer, but who know what future research will show? Based on this, I recommend that all infertile men certainly be evaluated by a urologist with a good history and physical examination. They should also be taught testicular self examination as a screening tool to detect testis cancer.
Infertility as a window into men’s health? As a shift in thinking, it certainly does shine a new light on the problem.