Scientists measured baseline levels of PSA in blood collected from 4,383 men aged between 20 and 94 years of age from the general population, who had taken part in the Copenhagen City Heart Study and followed them from 1981 through to 2009. Scientists measured baseline levels of prostate specific antigen and investigated whether this correlated with subsequent prostate cancer incidence and mortality.

During the 28 years of follow-up covered by the Heart Study, 170 men in the sample developed prostate cancer and 94 died from the disease. Measuring the antigen levels, the scientists found that stepwise increases in PSA predicted a 3-44 fold increased risk of prostate cancer and a 2-12 fold increased risk of prostate cancer mortality.

They also found that the absolute 10-year risk of prostate cancer was 11% to 22% in those with prostate-specific antigen levels of 4.01-10.00 ng/mL and 37% to 79% in those with levels above 10.00 ng/mL.

Dr. David Ørsted at the Copenhagen University Hospital, (Herlev, Copenhagen) commented, "The high risk for some men is probably due to some of the participants having already developed subclinical prostate cancer at the time of their entry to the study. These men would have had a shorter time from study entry to diagnosis and consequently, higher risk estimates."

According to European Cancer Observatory statistics, over 70,000 men die from prostate cancer in the EU every year. Prostate cancer and benign enlargement of the prostate gland (benign prostatic hyperplasia) share common features. Growth of the gland is dependent on hormone levels in both conditions and both respond to antiandrogen treatment, but until now, benign prostatic hyperplasia has not been considered a precursor to the development of a tumor.

Prostate-specific antigen is a protein produced by the prostate gland. Healthy men have low levels of the antigen in their blood, and raised levels are considered an indicator of prostate cancer as well as other conditions of the gland. However, it is largely unknown whether antigen levels in healthy men predict long-term risk of developing prostate cancer.

The ranges are wide and the higher risk for some men can be interpreted, Dr. Ørsted explains. "The high risk for some men is probably due to some of the participants having already developed subclinical prostate cancer at the time of their entry to the study. These men would have had a shorter time from study entry to diagnosis and consequently, higher risk estimates."

The results could be used to target specific sections of the population for screening. Dr. Ørsted added, "One of the major problems in prostate cancer is over-diagnosis. Furthermore, two large randomized studies have shown that the benefit of general screening for prostate cancer is limited. Our results indicate that physicians could focus screening efforts on men with higher baseline prostate specific antigen values while men with lower levels could avoid having frequent and unnecessary diagnostic examinations. This could reduce over-diagnosis and unnecessary treatment as well as reduce expenditure in already strained health systems."

The study was presented at the 2011 European Multidisciplinary Cancer Congress on September 24, 2011, in Stockholm Sweden.

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