Later preparations of PC-SPES, which contained less diethylstilbestrol and indomethacin than earlier preparations, showed a corresponding decrease in anticancer potency by as much as sixfold. The findings appear in the September 4 issue of the Journal of the National Cancer Institute.
PC-SPES ("PC" stands for prostate cancer, "SPES" is Latin for hope) is a mixture of seven medicinal herbs plus saw palmetto; it was introduced in the United States as a dietary supplement in 1996. Early studies suggested that the preparation was effective in reducing levels of prostate-specific antigen (PSA, a marker for prostate cancer) in both hormone-responsive and hormone-resistant prostate cancer patients.
However, concern grew because of evidence that the preparations were being contaminated with synthetic drugs, says Jeffrey White, M.D., of the National Cancer Institute, in an accompanying editorial. Subsequent studies found that PC-SPES contained the synthetic estrogen diethylstilbestrol, the anti-inflammatory drug indomethacin, and the blood thinner warfarin. Earlier this year, BotanicLab, the California-based manufacturer of PC-SPES, voluntarily recalled the product and has since gone out of business.
In this analysis of eight lots of PC-SPES manufactured at different times between 1996 and 2001, Milos Sovak, M.D., of the Biophysica Foundation in La Jolla, Calif., Robert Nagourney, M.D., of Rational Therapeutics, Inc., Long Beach, Calif., and their coworkers found that all lots contained indomethacin and most of the lots contained diethylstilbestrol. Warfarin began appearing in varying amounts in lots manufactured after Jul
Contact: Linda Wang
Journal of the National Cancer Institute