Men who cannot produce sperm are more prone to developing cancer than the general population, a new study has revealed.

The study also found that a diagnosis of azoospermia - infertile because of an absence of sperm in their ejaculate - before age 30 carries an eight-fold cancer risk.
Lead author Michael Eisenberg, MD, PhD, assistant professor of urology at the medical school and director of male reproductive medicine and surgery at Stanford Hospital and Clinics, said that a man suffering from azoospermia has a risk for developing cancer similar to that for a typical man 10 years older.

He said that there is evidence that infertility may be a barometer for men`s overall health, asserting that a few studies have found an association of male infertility with testicular cancer.

Eisenberg said that the new study not only assigns the bulk of infertile men`s increased cancer risk to those with azoospermia, but also suggests that this risk extends beyond testicular cancer.

The study population consisted of 2,238 infertile men who were seen at a Baylor andrology clinic from 1989 to 2009. Their median age was 35.7 when they were first evaluated for the cause of their infertility. Of those men, 451 had azoospermia, and 1,787 did not. There were otherwise no apparent initial differences between the two groups.

After undergoing a semen analysis, the men were followed for an average of 6.7 years to see which of them turned up in the Texas Cancer Registry.

Their rates of diagnosed cancer incidence were then compared with age-adjusted cancer-diagnosis statistics of Texas men in general.

In all, a total of 29 of the 2,238 infertile men developed cancer over a 5.8-year average period from their semen analysis to their cancer diagnosis. This contrasted with an expected 16.7 cases, on an age-adjusted basis, for the male Texas population in general.

This meant that infertile men were 1.7 times as likely to develop cancer as men in the general population. This is considered a moderately increased risk.

But comparing the cancer risk of azoospermic and nonazoospermic infertile men revealed a major disparity: The azoospermic men were at a substantially elevated risk - nearly three times as likely to receive a diagnosis of cancer as men in the overall population.

Infertile men who weren`t azoospermic, in contrast, exhibited a statistically insignificant increased cancer risk of only 1.4 times that of men in the overall population.

By excluding men whose cancer diagnosis came within two or three years of their infertility evaluation, the researchers were able to rule out the possibility that azoospermia caused by an undiagnosed cancer had affected the statistics.

The findings suggest that genetic defects that result in azoospermia may also broadly increase a man`s vulnerability to cancer, Eisenberg said, supporting the notion that azoospermia and cancer vulnerability may share common genetic causes.

The study has been published online in Fertility and Sterility.