British researchers have identified five distinct types of prostate cancer, and have found a way to distinguish between them.

The breakthrough study could have a major impact on how doctors treat prostate cancer because doctors will be able to identify cancers that are more aggressive and likely to spread.

Researchers from Cancer Research U.K. Cambridge Institute and Addenbrooke's Hospital, studied samples of healthy and cancerous prostate tissue from more than 250 men.

The scientists searched for abnormal chromosomes and measured the activity of 100 different genes linked to prostate cancer. They found the tumors fell into five distinct types, each with a specific genetic fingerprint.

By being able to tell the tumors apart, the researchers were more accurate at predicting which cancers were more likely to be aggressive than tests currently used, including the PSA and Gleason score.

"Our exciting results show that prostate cancer can be classified into five genetically different types," said Dr. Alastair Lamb, the study's author. "These findings could help doctors decide on the best course of treatment for each individual patient, based on the characteristics of their tumor.

"The next step is to confirm these results in bigger studies and drill down into the molecular 'nuts and bolts' of each specific prostate cancer type," Lamb said. "By carrying out more research into how the different diseases behave, we might be able to develop more effective ways to treat prostate cancer patients in the future, saving more lives."

According to the American Cancer Society, about 1 in 7 men will be diagnosed with cancer during their lifetimes. About 220,800 new cases of prostate cancer are diagnosed in the U.S. every year, and about 27,540 men die from the disease.

Professor Malcolm Mason, Cancer Research UK's prostate cancer expert, said: "The challenge in treating prostate cancer is that it can either behave like a pussycat — growing slowly and unlikely to cause problems in a man's lifetime — or a tiger — spreading aggressively and requiring urgent treatment. But at the moment we have no reliable way to distinguish them. This means that some men may get treatment they don't need, causing unnecessary side effects, while others might benefit from more intensive treatment.

"This research could be game-changing if the results hold up in larger clinical trials and could give us better information to guide each man's treatment, even helping us to choose between treatments for men with aggressive cancers," said Mason. "Ultimately this could mean more effective treatment for the men who need it, helping to save more lives and improve the quality of life for many thousands of men with prostate cancer."

The research was published in EBioMedicine.