Finasteride does not seem to cause high-grade prostate cancer

September 11, 2007

NEW YORK (Reuters Health) - Findings from two studies suggest that the previously reported link between finasteride use and high-grade prostate cancer is simply the result of detection bias, not a true causative association.

The results of the Prostate Cancer Prevention Trial (PCPT) had suggested that while finasteride use may reduce the overall risk of prostate cancer, it is associated with an increased risk of high-grade disease.

In one of the current studies, which is reported in the September 11th online issue of the Journal of the National Cancer Institute, Dr. Yael Cohen, from Gamida Cell in Jerusalem, and colleagues hypothesized that finasteride use does not cause high-grade prostate cancer, but rather shrinks prostate volume, making advanced disease easier to detect.

In analyzing data from nearly 1000 men enrolled in PCPT, the researchers found that prostate volume was, in fact, reduced with finasteride use. The median volume in users of the drug was 25% lower than in subjects given placebo.

After adjusting for prostate size, the authors found no elevated risk of high-grade prostate cancer with finasteride use.

In the second study, reported in the same journal issue, Dr. M. Scott Lucia, from the University of Colorado Health Sciences Center in Denver, and colleagues examined whether finasteride causes histologic changes so that low-grade prostate cancer may be mistaken for high-grade disease. The researchers evaluated biopsy data from 222 finasteride users and 306 controls enrolled in PCPT.

There was no evidence that finasteride altered prostate morphology so that low-grade malignancies could have been confused with high-grade disease. However, as in the first study, finasteride use did seem to reduce prostate volume, possibly facilitating detection of higher grade disease.

In a related editorial, Dr. Gerald L. Andriole, from Washington University School of Medicine in St. Louis, and colleagues comment that "taken together, the studies by Lucia et al. and Cohen et al. provide substantial reassurance that the increased proportion of high-grade cancer on biopsy in PCPT is not likely to be clinically relevant."