Finasteride May Prevent Development of Prostate Cancer

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Title: Finasteride May Prevent Development of Prostate Cancer
URL: http://www.pslgroup.com/dg/221A36.htm
Doctor's Guide
May 19, 2008

PHILADELPHIA -- May 19, 2008 -- A comprehensive re-evaluation of the largest prostate cancer prevention study ever completed produced findings that suggest that men and their physicians should consider finasteride to prevent the development of prostate cancer. The results appear in the June issue of Cancer Prevention Research.

The original study, the Prostate Cancer Prevention Trial (PCPT), randomised 18,822 men to receive either a placebo or finasteride for 7 years. The results of PCPT showed that finasteride reduced prostate cancer risk by 25%, and it may increase the development of more aggressive prostate cancer in some men.

From a new analysis of PCPT data using advanced statistical modelling techniques and a complete assessment of prostate tissue biopsies, the study authors concluded that these concerns are now resolved.

They found that finasteride actually reduced the risk of developing prostate cancer more than originally thought; finasteride did not increase development of more aggressive cancers; and the majority of tumours prevented were those that could spread and cause mortality.

Researchers also looked at whether finasteride actually increased aggressive cancers in some men, and by studying biopsies and prostate gland tissue that had been removed. They concluded that it did not.

"Finasteride actually shrank the prostate gland, so it appeared in initial studies that more cancer was being found in biopsies of men who took the drug," said Mary Redman, PhD, Biostatistician, Fred Hutchinson Cancer Research Center, Seattle, Washington.

Dr. Redman also found that -- in addition to a 25% to 30% reduction in prostate cancer development overall in men taking finasteride -- there was no evidence that the drug increased the rate of aggressive tumours and likely decreased their rate by 27%.

A pathologic analysis of that same study also shed light on the significance of the cancers found in the study.

The analysis examined whether the cancers detected in the men in the trial who had a low prostate-specific antigen (PSA) level had clinically significant disease. Nearly 75% of the tumours detected on the study were classified as those that could be potentially fatal, so researchers concluded that there was no clear-cut PSA threshold that can be considered normal.

All patients in the PCPT study had a biopsy of their prostate gland during the 7-year trial, so investigators evaluated characteristics of the biopsy in relation to each man's PSA score.

What they found, according to lead author Scott Lucia, MD, Pathologist, University of Colorado, Denver, Colorado, was that while a large majority of the participants diagnosed with prostate cancer had a PSA that was considered normal, 72% of all tumours diagnosed from biopsies in both treated and untreated men were considered significant.

The finding of significant disease could not be predicted by the PSA score, noted Dr. Lucia. Most patients in the study who had a PSA score of 4 or less and then had prostate cancer diagnosed by a routine biopsy were found to have significant prostate cancer, while some men who had a high PSA were found to have insignificant cancer.

That does not mean that the researchers support reducing the level by which PSA scoring should trigger therapeutic intervention, Dr. Lucia said.

"Over 90% of men in the country diagnosed with prostate cancer opt for treatment, yet we also found that even at higher PSA levels, men are being treated for tumours that would not have threatened their health," Dr. Lucia said.

"This is the dilemma of PSA screening. While lower cut-off levels, those below 4, increase risk of detection of insignificant disease, cure is more likely; conversely, more significant disease is detected with higher levels but at a greater risk of incurable disease."

SOURCE: Cancer Prevention Research

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