PC-SPES Has "Potent Estrogenic Activity" In Prostate Cancer

The popular herbal mixture PC-SPES has been found to decrease serum testosterone concentrations and lower prostate-specific antigen levels in prostate cancer, suggesting further study is needed.

According to an eight-patient study published in the Sept. 17 New England Journal of Medicine by Robert DiPaola, MD, et al., Robert Wood Johnson Medical School, the data "demonstrate that unregulated, commercially available dietary supplements may have biologic activity that can affect diseases, standard medical therapy and general health."

The researchers' studies suggest the mixture "may prove useful in the treatment of hormonally sensitive prostate cancer; but when used concurrently with standard or experimental therapies, PC-SPES may confound the results."

For example, all eight patients in the study experienced side effects similar to estrogen treatment, i.e., breast tenderness and loss of libido, in addition to having decreases in their serum testosterone and PSA levels.

Also of potential concern but certainly of interest, the researchers found the multiple organic compounds present in the mixture were not the known estrogens of "estrone, estradiol and diethylstilbestrol or chemicals with similar structure and mechanisms."

They tentatively conclude "multiple phytoestrogens may be responsible for the observed activity."

The mixture contains eight herbs: chrysanthemum, isatis, licorice, Ganoderma lucidum, Panax pseudo-ginseng, Rabdosia rubescens, saw palmetto and skullcap.

PC-SPES is promoted as nonestrogenic, the researchers note. However, they add, "licorice is known to compete with estradiol in an estrogen-receptor binding assay and ginseng induces estrogen-related expression of pS2, a small protein found in breast cancer, in cultured MCF-7 breast cancer cells," with the "clinical implication...unknown."

According to data they cite, the use of alternative medicine, including herbals, by cancer patients ranges from as low as 5% to as high as 60%.