Men who are infertile because they produce no sperm may have a
higher-than-average risk of developing cancer, a new study finds.
Researchers found that of more than 2 000 men with fertility problems, those
with no sperm production had an increased risk of developing cancer over the
next six years.
The men were young going into the study (about age 36, on average), so few
did develop cancer. Among men with no sperm -- what doctors call azoospermia --
just over 2% were diagnosed with cancer.
Still, their risk was three times higher than that of the average man their
"They have the cancer risk of a man about 10 years older," said lead
researcher Dr Michael Eisenberg, an assistant professor of urology at Stanford
University School of Medicine.
About 15% of infertile men are azoospermic, according to the study.
This isn't the first work to connect male infertility to cancer risk, but it
suggests the link may be concentrated among men with the most severe type of
"This suggests that it's not male infertility in general, but azoospermia in
particular," Eisenberg said.
A real link
That's an important piece of information, said a male-infertility expert not
involved in the study. If the link between male infertility and cancer is real,
you would expect that more severe infertility would be tied to a greater cancer
risk, said Dr Thomas Walsh, of the University of Washington in Seattle.
"This reinforces the idea that this is a real relationship," Walsh said.
He said he doubts anyone would say that infertility is causing cancer. But he
and Eisenberg said it's possible that some common genetic factors contribute to
both azoospermia and a greater vulnerability to cancer.
"When we see a man with azoospermia, we usually assume there's a genetic
cause," Eisenberg said. There are certain gene mutations already tied to the
condition, but a minority of azoospermic men turn out to have one of them when
they are tested. That means there are likely other, as yet unknown, gene defects
involved in azoospermia, Eisenberg said.
And some of those genetic flaws might be involved in cancer susceptibility,
Another infertility expert was cautious about interpreting the findings
because of the small numbers: only 10 cases of cancer among the 451 men with
azoospermia, and 19 cases among nearly 1 800 men with other types of
The idea that genetic abnormalities might underlie both azoospermia and
cancer risk has merit, said Dr Frederick Licciardi of NYU Langone Medical Center
in New York City. But, he said, "while this is important reasoning and is based
in basic science studies, I do not feel they have enough evidence in this paper
to bolster this theory."
Another question is whether azoospermia is linked only to certain cancers.
Past studies, including one Walsh worked on, have found that infertile men show
a higher than average risk of testicular cancer -- a highly curable disease
usually diagnosed in young men.
Of the 10 cancers in azoospermic men in this study, two were testicular
tumours. The others included brain cancer, prostate cancer, lymphoma and
Eisenberg said there were too few cases of each cancer to see whether men
with azoospermia were at particular risk for any one type.
For now, he recommended that men with the condition "be aware of the possible
risk, and pay attention to your health". That includes not only maintaining a
healthy lifestyle, he said, but also doing what most younger men do not -- seeing
your doctor for a regular check-up.
"It's too early to make any recommendations about cancer screening," he said.
But a routine visit to your doctor for a physical exam -- which can detect
testicular cancer, for example -- is wise, Eisenberg said.
Licciardi agreed. "Any man -- very low sperm count or not -- should have
regular physical examinations."
Walsh said much more research is needed to dig into the connection between
male infertility and cancer, including studies that follow men over a long
period, since cancer rates climb with age, as well as basic lab research to try
to uncover the reasons for the link.
Learn more about male
infertility from the American Society for Reproductive Medicine.