Test spots cancer years early

A single prostate cancer screening test before age 50 can help predict which men might develop aggressive forms of the disease, even 25 years before a diagnosis, researchers say.

The findings, published in BMC Medicine, could help doctors identify men who would benefit most from intensive screenings as they get older, the US and Swedish researchers said.

Prostate cancer is the second-leading cancer killer of men after lung cancer. Each year, some 680 000 men worldwide are diagnosed with the disease and about 220 000 will die from it.

Tests that look for a compound called prostate specific antigen or PSA can help detect cancer before men experience symptoms such as an enlarged prostate.

A very strong predictor
"A single PSA test taken at or before age 50 is a very strong predictor of advanced prostate cancer diagnosed up to 25 years later," the team at Memorial Sloan-Kettering Cancer Centre in New York and Sweden's Lund University wrote.

"This suggests the possibility of using an early PSA test ... so that men at highest risk are the focus of the most intensive screening efforts."

The findings follow a number of recent advances in prostate cancer.

Last week, three studies identified at least 10 new genes that raise a man's risk of prostate cancer, and U.S. researchers said on Thursday they had detected a biomarker that may help predict if a man's prostate cancer will return after surgery.

Previously, the team had showed that a single PSA test could predict the presence of prostate cancer in men up to 25 years before diagnosis. The latest findings extend that to determining those most at risk of aggressive forms of the disease.

A higher PSA when young makes a person more likely to get the slow-growing cancer, which in turn has more time to mutate and spread to other parts of the body, said Andrew Vickers, a cancer specialist at Sloan-Kettering who worked on the study.

Early signs
"What we are thinking is long before you get a prostate cancer detected, there is some kind of change going on and PSA is leaking into the blood," he said in a telephone interview.

The researchers based their findings on an analysis of blood samples collected between 1974 and 1986 as part of a large study in Malmo, Sweden, that included 161 men who eventually developed advanced prostate cancer.

A majority of these men who developed aggressive prostate cancer that spread to other parts of the body had PSA levels in the top 20 percent. The average length of time from blood test to cancer diagnosis was 17 years. – (Reuters Health)

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Prostate Centre

February 2008