Five different recipes of prostate cancer have been identified, with major implications for the way the disease is treated.
The "five ways" discovery was made by scientists who studied samples of healthy and cancerous tissue from more than 250 men.
Tumours were grouped into five distinct categories based on the activity of 100 different genes.
Each had a characteristic genetic fingerprint, the study showed. The analysis was better at spotting deadly cancers than tests currently used by doctors, including the PSA (Prostate Specific Antigen) blood marker and Gleason score aggressiveness rating.
Lead researcher Dr Alastair Lamb, from the Cancer Research UK Cambridge Institute, said: "Our exciting results show that prostate cancer can be classified into five genetically-different types. These findings could help doctors decide on the best course of treatment for each individual patient, based on the characteristics of their tumour.
"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. By carrying out more research in to 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."
Each year around 41,700 men in the UK are diagnosed with prostate cancer and 10,800 die from the disease.
Prostate cancer is the most common cancer in men in the UK, with around 41,700 cases diagnosed every year. There are around 10,800 deaths from the disease each year in the UK.
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.
"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."