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"To my knowledge, this is the first study to identify a link between male factor infertility and prostate cancer," said Dr. Thomas J. Walsh, an assistant professor of urology at the University of Washington, and lead author of a report published online March 22 in the journal Cancer.
There have been hints in previous studies of such a link, Walsh said, but those studies had a built-in bias, since they looked specifically at men who were screened by urologists because they were identified as being infertile, rather than comparing their risk of prostate cancer with that of all other men.
The new study avoided that bias by using a statewide database of prostate cancer cases maintained in California. The incidence of prostate cancer in that general population was compared with the incidence of prostate cancer in 22,562 men evaluated for infertility at 15 California centers between 1967 and 1998.
The overall incidence of prostate cancer in the two groups was about the same, the study found. But a difference emerged when the aggressiveness of the tumors was measured by the Gleason score, which looks for degree of abnormal organization of a prostate tumor. A higher Gleason score is an indicator of aggressive growth, and the incidence of cancers with high Gleason scores was 2.6 times higher in the infertile men.
There are several possible explanations for the relationship, none of them as yet proven, Walsh said. "There could be underlying genetic abnormalities on the male chromosome," he said. "Also, these men may have a deficit in their ability to repair DNA; there is some evidence that this may be the underlying cause."
But there are indications that the increased risk may be related in some way to male hormones, Walsh said. Studies have found a lower risk of prostate cancer in men who grow bald earlier in life, he said, and baldness is often caused by androgen activity.
The apparent link between infertility and increased prostate cancer risk can be put to medical use, Walsh said. When inability to father children is suspected, "we may want to screen these men more aggressively for prostate cancer," he said.
The finding "may provide clues as to how we can identify the underlying reasons why some prostate cancers are aggressive and most aren't," said Robert A. Smith, director of cancer screening for the American Cancer Society.
It may also add a factor to be considered when the issue of screening comes up, Smith said. The society does not recommend routine screening with a test for prostate-specific antigen, he noted, but says the issue should be made on the basis of individual factors, such as family history. Infertility may become such a factor, Smith said.
But since this is a first study, "it needs to be confirmed in other populations of men," Walsh said. "It is up to scientists to confirm the findings and do basic research to enable us to understand the link."
And men who might have fertility problems need not panic about cancer, he said. "The absolute risk of cancer is still very low," Walsh said. "No man need be alarmed unduly."
Copyright © 2010 HealthDay. All rights reserved.
SOURCES: Thomas J. Walsh, M.D., assistant professor, urology, University of Washington, Seattle; Robert A. Smith, Ph.D., director, cancer screening, American Cancer Society, Atlanta; March 22, 2010, Cancer, online