Data Suggest Finasteride May Aid In Preventing Prostate Cancer

A re-analysis of a landmark prostate cancer study shows that the drug Finasteride may play a role in a more aggressive approach to preventing prostate cancer. The study will appear online in the June 2008 issue of the journal Cancer Prevention Research. 

The original study, called the Prostate Cancer Prevention Trial (PCPT), followed nearly 19,000 men for seven years, ending in 2003. Study participants were randomized into a placebo group and a group that took finasteride, a drug approved for use in controlling prostate growth. According to the original analysis, the drug reduced prostate cancer risk in the group taking it by 25 percent but also appeared to increase the incidence of more aggressive prostate cancers in some of the study participants in the finasteride group.

Due to that finding and another that showed that the aggressive prostate cancers had low prostate specific antigen (PSA) scores and might pose little risk to patients, doctors have been reluctant to prescribe finasteride.

But the new analysis to be published in Cancer Prevention Research in June 2008 led researchers to conclude that finasteride actually reduced prostate cancer risk more than the original analysis had shown. In addition, researchers write, the drug did not increase development of more aggressive prostate tumors. Moreover, the majority of tumors prevented appeared to be of a type more inclined to spread.

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

The researchers found that in addition to a 25 percent to 30 percent reduction in prostate cancer development overall in men taking finasteride, there was no evidence that the drug increased the rate of aggressive tumors and likely decreased their rate by 27 percent.

The second study examined whether the cancers detected in the men in the trial who had a low PSA level had clinically significant disease. With about 75 percent of the tumors detected on the study were classified as those which could potentially take a man’s life, researchers concluded that there is no clear-cut PSA threshold that can be considered normal.

All patients in PCPT were to have a biopsy of their prostate gland at some point during the seven-year trial, so investigators evaluated characteristics of the biopsy in relation to each man’s PSA score. Current practice is to consider a PSA score of below four as normal and above four as abnormal.

What they found, according to lead author Scott Lucia, M.D., a pathologist at the University of Colorado, Denver, was that while a large majority of the participants diagnosed with prostate cancer had a PSA that was considered normal, 72 percent of all tumors diagnosed from biopsies in both treated and untreated men were considered significant. In short, the finding of significant disease couldn’t be predicted by the PSA score, he said. Most patients in the study who had a PSA score of four 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.

Source: American Association for Cancer Research