Men who develop testicular cancer father fewer children and are more likely to have been diagnosed with infertility problems prior to their cancer diagnosis, researchers have found.

The study, by a team from the University at Buffalo, contradicts earlier findings that showed no relationship between a man's fertility and eventual diagnosis of testicular cancer.

The Buffalo team found that men who were eventually diagnosed with testicular cancer were two-thirds less likely to have ever fathered a child, and were nine times more likely to have been diagnosed as infertile than healthy men.

In total 201 cancer patients and 204 healthy controls took part in the study.

Undescended testes

Testicular cancer is associated with a condition called cryptoorchidism, or undescended testes at birth.

Lead researcher Julie Baker said: "We had been thinking that these men were normal until they developed tumours and then they got sick.

"Now we think they have been sick all along."

Dr Germaine Buck, associate professor at the University of Buffalo, said: "Having difficulty impregnating a woman may be just one manifestation of having unhealthy testes that will eventually develop cancer."

Dr Buck said that if the findings of the study could be replicated, it may suggest that clinicians should keep a close eye on men who reported fertility problems.

She said it was good policy for all men to examine their testes regularly for lumps.

The researchers plan further studies to try to isolate the cause of the cancer. It is thought that environmental pollutants may cause the disease by disrupting the hormonal system.

The previous study, carried out by the Roswell Park Cancer Institute also in Buffalo, focused on men with the most aggressive forms of testicular cancer.

Ms Baker said her study was probably more representative.

Testicular cancer is still relatively uncommon in the UK, but the number of cases appears to be increasing, particularly among young men.