A new prostate cancer test could prevent the unnecessary treatment of thousands of men by predicting whether a tumour will be aggressive or slow-growing, researchers have claimed.
Prostate cancer is the most common cancer among British men, with more than 40,000 cases diagnosed each year, but in many cases the disease is so slow to develop that it will never cause any symptoms in the patient's lifetime.
Blood tests for a protein known as PSA, or prostate specific antigen, have sharply increased diagnosis rates but do not reveal whether a tumour is likely to be slow or fast-acting.
It means that while more men than ever before are being diagnosed with prostate cancer, many are given aggressive treatment despite having a relatively harmless form of the disease.
Prof Jack Cuzick, of Queen Mary University of London, explained: "Overtreatment of prostate cancer is a serious issue so it's essential that we have an accurate way of spotting those cancers that pose an immediate risk.
"For patients with slow-growing tumours, it’s far safer and kinder to watch and wait – only acting if the situation starts to change."
Prof Cuzick will present a new method for distinguishing between aggressive and less dangerous tumours at the National Cancer Research Institute (NCRI) Cancer Conference in Liverpool on Tuesday.
The Prolaris test, developed by Prof Cuzick and other Cancer Research UK scientists, measures the activity of a set of genes known as cell cycle genes, which help drive the division of cells in the body.
After performing the test on a biopsy of a tumour, scientists can assign the cancer a "cell cycle progression" (CCP) score based on how active its genes are.
A higher CCP score indicates a greater amount of activity and suggests that a tumour is likely to grow more rapidly, meaning patients would benefit from rapid treatment.
Cancers with lower scores are likely to be less severe, meaning doctors could place the patient under "active surveillance" and continue to monitor the tumour rather than treating it immediately.
A retrospective analysis of results from five different, prior studies of biopsy tissue suggested that the test could tell different tumour types apart at various different stages of treatment.
Prof Cuzick said: “We still need to work out how best to use this test to help patients. We want to try and shorten the time it takes to get the results and establish how frequently the test needs to be done in order to be most effective at spotting any changes.
Dr Harpal Kumar, chief executive of Cancer Research UK and chair of the NCRI, added: “Being able to tell apart aggressive and slow-growing tumours would help us take a major step forward in prostate cancer treatment.
"Understanding more about the nature of a patient’s tumour could spare thousands of men from unnecessary treatment and the resulting side effects, whilst also meaning that those who do need treatment receive it rapidly.”