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Study Finds Additional Evidence For Contamination Of Herbal
Supplement For Prostate Cancer September 4, 2002 (Journal of the National Cancer Institute) -- A chemical analysis of PC-SPES,
a recently recalled herbal dietary supplement commonly used to treat advanced prostate
cancer, has shown that the supplement was contaminated with the synthetic drugs warfarin,
diethylstilbestrol and indomethacin. Diethylstilbestrol and indomethacin
have known anticancer properties. 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 July 1998. "The origin of the three potent synthetic drugs in PC-SPES is
puzzling," the researchers write. They note that the amount of diethylstilbestrol
present in the lots would have been enough to exert anticancer activity. Lots manufactured
after the spring of 1999 contained significantly less diethylstilbestrol and indomethacin
than earlier lots and had two to six times less anticancer activity. In his editorial, White says that "herbal research is complicated
enough without having to deal with the added problem of potential product
adulteration." He says that preclinical and clinical trial research of promising herbal
interventions should continue. However, he urges investigators to consider regular quality
control evaluations by independent laboratories throughout the course of their research. The lessons from PC-SPES must be learned well, he says, "because the
loss of a product that symbolized hope to some should not occur without leading to an
ultimate gain for all cancer patients."
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NANAY Inc. is supported by Florida Older Americans Act, Alliance for Aging for Miami-Dade and Monroe Counties, Florida Department of Transportation, Miami-Dade Alliance for Human Services, Dept of Health and Human Services, Miami-Dade County Office of Community and Economic Development, North Miami CDBG, Association of Asian Pacific Community Health Organizations (AAPCHO), National Asian Women's Health Organization (NAWHO), AETNA Foundation and United Way (Miami-Dade Reg. # 161126)
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