LONDON (Reuters) ¿ Three studies published this week identify at least ten new genes that raise a man's risk of prostate cancer, information which could lead to better screening and targetted drugs to treat the disease.

The US and European findings add to the number of known genetic variations linked with prostate cancer risk and may help, one day, predict which men are susceptible to the most aggressive forms of the disease, researchers said.

The teams published their independent studies in the journal Nature Genetics.

Ros Eeles, an oncologist at The Institute of Cancer Research in Britain, whose team identified seven new gene changes linked to prostate risk, said genetic tests based on the findings were a few years away.

"The results we have found today are a breakthrough as they have identified seven new areas of the genome associated with prostate cancer risk," she said.

"They have the potential to be developed into a genetic test. However, we consider that marketing of tests to the public is premature."

Prostate cancer, which becomes more likely as men get older, is the second most common cause of cancer death among men after lung cancer. Each year some 680,000 men are diagnosed with prostate cancer, and about 220,000 will die from it.

The cancer is also often a slow-growing tumour and many men will die of something else before it becomes dangerous. Detecting more of these genes is important because it could one day make it easier to pick out men at highest risk, Eeles said.

"These results could help decide who really needs screening," she told reporters in London.

In her study, the researchers studied the genetic make up of more than 10,000 men to pick out gene sequences found more often in men with prostate cancer. The prostate is a walnut-sized gland that makes fluid for semen. Researchers from Iceland's Decode Genetics Inc turned up two new genetic changes and the biotechnology company said it would offer a screening test available through a physician for $500 starting this week. "We believe that this is a test with significant clinical utility for improving and personalising the screening and treatment of one of the most common cancers," Decode's Chief Executive Kari Stefansson said in a statement. A host of companies now offer such genetic tests for common conditions like cancer, diabetes and heart disease but some scientists say they do little good and can saddle people with unnecessary anxiety or provide false reassurance.

Steven Chanock of the National Institutes of Health in the United States and colleagues detected three genetic changes in their study of more than 1,100 men with prostate cancer and those without the disease. Like the other studies, his team confirmed the findings in an independent population.