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-naïve 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.

In their initial stages of growth, prostate cancer cells require androgens, or the male hormone called testosterone, to survive. Hormone therapy is a method of reducing or eliminating a man's supply of testosterone to a prostate tumor. One method of achieving this is by giving a man the female hormone, estrogen, which counters the effects of testosterone and shuts down the gland in a man's brain that stimulates the testicles to produce hormones.

However, although prostate cancer cells require androgens to survive initially, tumors can become independent of these hormones. When this occurs, tumors develop the ability to grow and spread regardless of the circulating hormones in the body. This stage of disease is called androgen-independent or hormone-resistant prostate cancer.

"As our study continues, we ultimately hope to learn a number of things about PC-SPES," Small says. "For instance, we aim to determine what percentage of men with hormone-nave and hormone-resistant prostate cancer have declines in their PSA levels with use of the herbal compou
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Contact: Abby Sinnot
asinnot@pubaff.ucsf.edu
415-885-7277
University of California - San Francisco
18-May-1999