Two teams of scientists - from the UK and the US - have identified the first known inherited gene variants that predispose carriers to testicular cancer. Previous studies have highlighted genes that are active in testicular cancer cells but these studies, published together in the journal Nature Genetics, are the first to pinpoint inherited genetic causes of the disease.
The UK team, from the Institute of Cancer Research (ICR), London, analysed DNA from 730 men with testicular cancer and compared it to 1, 435 men with no history of the cancer. They identified gene variants located on chromosomes 5, 6 and 12 that were more commonly seen in men who developed testicular cancer compared to the healthy controls. These findings were then confirmed by screening DNA from a second set of individuals containing 571 testicular cancer patients and 1806 controls. Each gene variant individually increased the risk of testicular cancer by around one-and-a-half- to three-fold, and individuals carrying risk variants on all three chromosomes were about four times more likely to develop the cancer.
Dr Elizabeth Rapley, from the ICR team, said: 'we have known for some time that men whose father, brother or sons had testicular cancer are much more likely to get it themselves and we have been searching for this genetic link. In this research we have identified three genetic factors linked to an increased risk of testicular cancer. We believe there are still more to be found and we are working on the rest'.
The US team conducted a similar study on DNA samples from 277 men with testicular cancer and 919 healthy male controls, and confirmed their results in a second set of 371 testicular cancer cases and 860 controls. They pinpointed the same risky gene variants on chromosomes 5 and 12, and found that carriers of these genes in different combinations had a similarly increased risk of testicular cancer of around three- to four-and-a-half-fold.
Professor Mike Stratton, from the ICR and the Wellcome Trust Sanger Institute, said: 'by combining these genetic risks with other known risk factors it may be possible in future to identify men who are at high risk of developing testicular cancer...This may allow early detection or prevention'.
There are around 2000 new diagnoses of testicular cancer in the UK each year. It is seen mainly in young men and is the most common cancer in males aged between 20 and 35. The vast majority of cases are curable; however, if left untreated, the cancer can spread to the lymph nodes, lungs and occasionally other organs. Ed Yong, health information manager at Cancer Research UK, commented: 'finding the genes that increase the risk of this cancer is important. It tells us more about its basic biology and presents new opportunities to prevent, diagnose and treat the disease'.