Study Shows Herbal Therapy Reduces PSA Levels in Prostate Cancer

May 18, 1999
News Office: Abby Sinnott (415) 885-7277

In one of the first studies of its kind, UCSF Medical Center researchers have found that an herbal compound significantly reduced prostate specific antigen (PSA) levels, an indicator of cancer cells, in men with advanced prostate cancer.

In response to the herbal compound, 75 percent of the men in the study experienced more than a 50 percent decline in their PSA levels. Men in the study included those receiving hormonal therapy for the first time (hormone-naove) and patients with hormone-resistant prostate cancer, whose tumors no longer responded to hormonal therapies.

The compound, called PC-SPES ("PC" stands for prostate cancer, "SPES" is Latin for hope) is a combination of eight Chinese herbs, the most common of which is saw palmetto. It is commercially available at health food stores as an over-the-counter supplement to treat prostate cancer.

During the UCSF study, 61 men (27 with hormone-naove prostate cancer, and 34 with hormone-resistant prostate cancer) were clinically evaluated for preliminary results. Study participants received nine capsules daily of PC-SPES. The majority of these men are still enrolled in the clinical trial and continuing treatment at this time.

"Our findings suggest that PC-SPES may have efficacy as a treatment for some men with prostate cancer," said Dr. Eric Small, a urologist at UCSF Medical Center and co-author of the study. "However, as of yet, we cannot precisely pinpoint the estrogenic or active anti-cancer ingredients, if any, that PC-SPES may contain."

Small, a UCSF assistant clinical professor of medicine, reported that 27 (100 percent) of the hormone-naove patients experienced more than a 50 percent decline in their PSA levels. Likewise, 19 out of 34 (58 percent) hormone-resistant patients also demonstrated more than a 50 percent decline in their PSA levels.

The study's results are preliminary and require further evaluation and a longer follow-up period (minimum of two years), Small said. Although not all of the study participants were eligible for evaluation at this time, a total of 70 men have enrolled in the study and begun treatment with PC-SPES.

In addition, Small reports that shrinkage of some of the men's prostate cancer tumors was observed. Some of the side effects of the compound included impotency, lowered sex drive and breast tenderness -- all common conditions associated with hormonal therapies. However, overall, the therapy was well tolerated.

According to Small, PC-SPES may work in part like a hormonal therapy for prostate cancer because it demonstrated an anti-testosterone effect in hormone-naove prostate cancer patients by mimicking the female hormone, estrogen. The compound may contain other active anti-cancer ingredients because it also lowered PSA levels in men in the study whose tumors have become resistant to hormonal treatments.

Other authors of the paper include Dr. Robert Bok, clinical instructor of medicine; Michele Corry, UCSF registered nurse practitioner; Dr. Mark Frohlich, UCSF clinical instructor of medicine; Hiroko Kameda, UCSF research assistant; Dr. W.K. Kelly, urologist oncologist at Memorial Sloan-Kettering Cancer Center; and Dr. David Reese, UCSF assistant clinical professor of medicine. The study is supported by the Association for the Cure of Cancer of the Prostate.