A combination of three genetic abnormalities has a dramatic impact on how long prostate cancer patients are likely to live, researchers said on Wednesday, and gene tests could help doctors decide on the best treatments.

Scientists at Britain’s Institute of Cancer Research (ICR) said their findings showed prostate cancer patients should be tested for specific genetic factors before doctors decide how aggressively to treat their tumours.

Prostate cancer is the most common cancer in men and the second highest cause of male cancer-related deaths across the world, killing around 254,000 men a year.

Most cases are very slow-growing and would never kill the patient or even cause symptoms, but it is very difficult to predict whose tumours are likely to spread.

Alison Reid, who led the study, said it showed that patients with none of three specific genetic changes had good prospects, with 85.5 percent of them still alive after 11 years.

But those who had the all three gene abnormalities had a much worse prognosis, with only 13.7 percent of them still alive after 11 years.

Helen Rippon of the Prostate Cancer Charity said the study would help answer one of the most important questions in prostate cancer research - “how to distinguish early, and with confidence, the potentially life threatening prostate tumours from the slow-growing form of the disease”.

The ICR team used a technique called fluorescence in situ hybridisation (FISH) to analyse prostate tumour samples from 308 patients and look for three genetic changes - loss of the PTEN gene and rearrangement of the ERG or ETV1 genes.

Previous studies have shown that deletions of the PTEN gene and ERG gene mutations occur commonly in prostate cancer, but the combined impact of these on survival in a large group of patients had not been looked at previously.

Reid said around six percent of patients in the study had lost the PTEN gene and did not have either an ERG or ETV1 gene rearrangement. These were the patients at much higher risk of dying from their cancer.

“Men diagnosed with prostate cancer could be tested for all three genetic alterations, and this information could be used to help determine how aggressively they should be treated,” she wrote in the study in the British Journal of Cancer.

Colin Cooper, who also worked on the study and is part of the Transatlantic Prostate Group, said there was an urgent need to find biological markers like these to help distinguish between high- and low risk patients.

“Such a test could help us determine who requires radical, immediate treatment and who can receive less therapy and therefore be at lower risk of side-effects,” he said.

A study published last August found that routine screening for prostate cancer in the United States was turning out to be a double-edged sword - catching serious cancers in a few men but causing needless worry and expense for many others who were being treated for tumours growing too slowly to do any harm.

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* Three genetic factors combined make cancer more deadly

* Tests would help decide who needs aggressive treatment

By Kate Kelland

LONDON (Reuters)