Boys who are born with an undescended testicle, a condition known as cryptorchidism, are at increased risk of developing testicular cancer later in life, a new report suggests.
The report, which combined data from previous studies on the cancer-cryptorchidism connection in what is known as a meta-analysis, found that boys born with one or both testes undescended were three times as likely as others to develop cancer.
Cryptorchidism affects about 6 percent of all newborn boys. In some cases the testes descend on their own in the first few months of life. But, if they don't, doctors recommend surgery to correct the problem when the boy is between 6 and 18 months old.
That surgery is to protect the boy's fertility, not to prevent cancer, says the study co-author, Dr. Robert Carachi, a professor in the department of surgical pediatrics at the Royal Hospital for Sick Children in Glasgow.
If the testes were left inside the abdomen, the temperature would be too high and the boy would have fertility problems, Carachi explains.
Currently no one knows why boys with cryptorchidism have a higher rate of testicular cancer. It could be that the testes in these boys are abnormal to start out with and that would explain why they don't descend when they should and also why they are more likely to develop cancer, Carachi says.
For the new study Carachi and his colleagues scoured the medical literature for all articles relating to cryptorchidism and testicular cancer published between January 1980 and December 2010. They ultimately settled on 12 studies - 9 case-control studies that included 2,281 patients with testicular cancer that were compared to 4,811 healthy control subjects and three cohort studies that included two million boys, 345 of whom had been born cryptorchid and who had later developed testicular cancer.
The combined studies yielded a rate of testicular cancer among boys born with cryptorchidism that was 2.9 times that of their peers.
Even though the surgery doesn't lower the risk of cancer, it does put both testicles within reach so they can be regularly examined easily, says Dr. Michael Ost, an associate professor of pediatric urology at the University of Pittsburgh Medical Center and division chief of pediatric urology at the Children's Hospital of Pittsburgh of UPMC.
Ost says he tells parents what that increased risk of cancer means to their sons.
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"I tell them that the risk of cancer in males between the ages of 18 and 35 is one to three in 100,000 and this puts them at an increased risk," he says. "So they have to be diligent in terms of watching their children and examining them on a regular basis - and when they come of age, teaching them to examine themselves."
Even with the increase due to cryptorchidism, the risk is still fairly low, though.
A threefold increase means that instead of one to three cases of cancer out of 100,000 boys, there will be three to nine cases out of 100,000.
Still, says Ost, "it means that boys and men with a history of cryptorchidism just need to be more vigilant about doing self-exams."