NEW YORK (Reuters Health) - Results of a case-control study suggest an association between fertility and risk of prostate cancer, Swedish investigators report in the July 20th issue of the International Journal of Cancer.

"Men who are childless have an almost 20% lower risk of getting prostate cancer than those who have fathered two or more children," Dr. Aleksander Giwercman of Malmo University Hospital in Sweden told Reuters Health. Men with one child, he added, have a risk which falls between that of these two groups.

Dr. Giwercman and colleagues note that androgens are thought to play a key role in the development of prostate cancer, leading them to speculate that men who have fathered children might be at higher risk than childless men.

The researchers used the Swedish national cancer registry to assess male fecundity in relation to the risk of prostate cancer. The study, which involved 48,850 men with prostate cancer and an equal number of healthy controls, revealed such a link.

"However, among childless men there are probably three categories," Dr. Giwercman pointed out. "Those who are truly infertile/subfertile and have impaired testicular function; those who have a subfertile/infertile partner but have normal testicular function; and those who remained single or do not wish to have children. We suggest that the association between childlessness and prostate cancer risk is mainly due to the first group of men."

Men with impaired testicular function not only produce less sperm but also produce less testosterone, on average, he added. "Testosterone is known to be linked to the growth of the prostate cancer and we believe that our study provides indirect evidence of an association between testosterone production in young adulthood and subsequent prostate cancer risk, with those having subnormal testosterone production having a lower risk of getting prostate cancer."

Int J Cancer 2005;115:994-997

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