Men who are infertile as a result of a lack of sperm in their semen are at a significantly increased risk of developing cancer, a new study indicates.

Azoospermia refers to a condition in which a man has no measurable amount of sperm in his semen. It is thought to affect around 1% of men, but is seen in up to one in five cases of male infertility.

According to US scientists, there is increasing evidence that infertility ‘may be a barometer for men's overall health'. Furthermore, some studies have found a link between male infertility and testicular cancer.

They decided to look into this further. They analysed data on over 2,200 infertile men who attended a fertility clinic between 1989 and 2009. The average age of the men when they first attended was 35 years.

Over 450 of the men had azoospermia, while the remainder did not. All were monitored for an average of six years to see who, if anyone, developed cancer.

The scientists found that overall, infertile men were 1.7 times more likely to develop cancer compared to men in the general population. This is seen as a moderately increased risk.

However, when azoospermia was taken into account, a major disparity appeared. Those with the condition were almost three times more likely to go on to develop cancer compared to men in the general population.

"An azoospermic man's risk for developing cancer is similar to that for a typical man 10 years older," explained lead scientist, Dr Michael Eisenberg, of Stanford Hospital & Clinics.

Furthermore, azoospermic men who first had their semen analysed before they reached the age of 30 were over eight times more likely to develop cancer compared to men in the general population.

The scientists noted that the condition appeared to be linked to a range of different cancers, including testicular, prostate, stomach and brain cancer. They suggested that genetic defects that cause the azoospermia in the first place may also increase a man's risk of cancer.

The team said that young men who are diagnosed with azoospermia should be aware of their increased risk of developing cancer and have regular medical check-ups as a result.

Details of these findings are published in the journal, Fertility and Sterility.