Related Pages Search for Clinical Trials 1 NCI's PDQ® Cancer Clinical Trials Registry. Prostate Changes That Are Not Cancer 2 Part of the booklet, "Understanding Prostate Changes: A Health Guide for Men" -- includes discussion of BPH.

Reprinted from the NCI Cancer Bulletin, vol. 3/no. 7, Feb. 14, 2006 (see the current issue ³).

An extract of the saw palmetto plant was no more effective than a placebo in reducing symptoms associated with benign prostatic hyperplasia (BPH), a randomized clinical trial has found. BPH is caused by an enlarged prostate gland, and millions of older men, particularly in Europe, use over-the-counter saw palmetto products to treat the condition.

The double-blind, randomized trial included 225 men over age 49; half took 160 mg of saw palmetto twice daily, and the others a placebo. After a year, the groups were similar in lower urinary tract symptoms and other objective measures of BPH, the researchers report in the February 9, 2006, issue of the New England Journal of Medicine (see the journal abstract).

The study, led by Dr. Stephen Bent of the University of California, San Francisco, was funded by the National Institutes of Health and the National Center for Complementary and Alternative Medicine. The negative results contrast with a number of earlier studies suggesting that saw palmetto may improve urinary symptoms caused by BPH.

To explain the discrepancy between the positive and negative findings, the researchers point out that some earlier studies had design flaws. In addition, the patients in the new study may have shared attributes that made them unlikely to respond to saw palmetto. Alternatively, the level of the active ingredient in their extract may have been too low to be effective (the active ingredient, if one exists, is not known).

The study was well designed, adequately powered, and avoided the pitfalls of previous studies by treating participants for a year, optimizing the consistency of the herbal product, and measuring the adequacy of blinding, an accompanying editorial notes. The authors raise the possibility, however, that a different preparation or dose of saw palmetto might have been effective.

Glossary Terms

A benign (not cancer) condition in which an overgrowth of prostate tissue pushes against the urethra and the bladder, blocking the flow of urine. Also called benign prostatic hypertrophy and BPH.

A clinical trial in which the medical staff, the patient, and the people who analyze the results do not know the specific type of treatment the patient receives until after the clinical trial is over.

An inactive substance or treatment that looks the same as, and is given the same way as, an active drug or treatment being tested. The effects of the active drug or treatment are compared to the effects of the placebo.

A study in which the participants are assigned by chance to separate groups that compare different treatments; neither the researchers nor the participants can choose which group. Using chance to assign people to groups means that the groups will be similar and that the treatments they receive can be compared objectively. At the time of the trial, it is not known which treatment is best. It is the patient's choice to be in a randomized trial.