Researchers at Stanford University say infertility may put some men at higher risk of developing brain, prostate and testicular tumors as well as melanoma and lymphoma.
The scientists studied 2,238 infertile men around age 35 who were undergoing treatment at Baylor College of Medicine in Houston between 1989 and 2009. All of the men provided samples for semen analysis at the beginning of the study; 451 had azoospermia, or no sperm in their ejaculate. Of the four million men in the US affected by infertility, about 600,000, or 1% of have azoospermia, which can be caused by blockages in the reproductive tracts of the testes that prevent normal volumes of sperm from populating the ejaculate, or inadequate production of sperm.
In total, among the participants, 29 developed cancer over the nearly six year study period, with the highest rates occurring among men with azoospermia. To ensure that the results were not confounded by the fact that a cancer diagnosis might be responsible for the lack of sperm, the researchers excluded men who developed cancer within a few years of the semen analysis.
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That rate of cancer diagnosis was significantly higher than that expected for males in the Texas region, say the scientists. Overall, the infertile men were 1.7 times as likely to develop cancer compared to the general population, but the azoospermic men were three times as likely to develop cancer compared to the general public. The researchers were particularly concerned about the younger men in their study; men who developed azoospermia before age 30 were eight times as likely to develop cancer than fertile men their age.
Because of the range of different cancers that the men developed, the researchers say it’s difficult to speculate on why the inability to make sperm might be connected with a higher risk of tumors. They suspect, however, that a still-unidentified genetic defect may be driving the two conditions.
That possibility underscores the importance of considering infertility as a bellweather for a man’s health, says the study’s lead author, Dr. Michael Eisenberg, assistant professor of urology and director of male reproductive medicine and surgery at Stanford Hospital & Clinics. “There is evidence that infertility may be a barometer for men’s overall health,” he said in a statement. If that’s the case, then azoospermia in particular could be a early warning for young men who might be at higher risk of developing cancers, and the infertility diagnosis, says Eisenberg, should serve as an opportunity for them to be more vigilant in monitoring for potential tumors.
The study is published in the journal Fertility and Sterility.