Scientists say they have developed a clever way to predict how prostate cancers will behave.
How aggressive the tumour is will determine its treatment
The "Checkerboard" method looks for markers of cancer genes in multiple tissue samples taken using tiny needles inserted into the prostate gland.
By building a picture of which genes are present, some denoting more dangerous tumours, doctors should be able to better predict best treatment.
The Institute of Cancer Research work is in the British Journal of Cancer.
Currently, doctors rely on blood, urine and tissue samples to predict how aggressive - likely to spread - prostate tumours are.
Some tumours will spread quickly and can kill, while others may need no immediate treatment and can be closely monitored instead.
However, these methods are not accurate and clinicians have to rely on their judgement to decide whether to operate or not.
The new Checkerboard technique will be an added help in this process.
Numerous tiny blocks of tissue, obtained by needle biopsy, are fixed in a check pattern for examination in the lab.
These can be analysed simultaneously for known gene markers linked to prostate cancers.
One that can be screened for is a marker of the gene E2F3, which gives an indication of how aggressive a cancer will be.
Avoiding unnecessary surgery
The analysis of multiple markers is important because it may be the analysis of a combination of markers rather than a single marker that provides the best prognostic information, scientists believe.
Professor Colin Cooper from the Institute of Cancer Research said: "Eventually we hope to be able to distinguish the tigers - aggressive tumours requiring treatment - from the pussycats - non-aggressive tumours which can be monitored for many years without treatment.
"Ultimately, this could prevent thousands of men from having to undergo radical surgery, which can have devastating effects on their day to day life."
Dr Chris Hiley of The Prostate Cancer Charity said: "The difficulty that confronts many men and their doctors is in establishing whether a man's prostate cancer will be so slow growing that he may not need treatment or whether it is potentially life threatening and he does.
"If the technique is proven...it will enable doctors to predict the behaviour of individual prostate cancers, so that men will receive the most appropriate treatment.
"It is a step in the right direction and we await further evidence of its practical benefits.¿
Prostate cancer is now the most common cancer to affect men in the UK - more than 30,000 are diagnosed with it each year.