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Study Sheds New Light on Cancer-Fighting Potential of Herbal Supplement for Prostate Cancer

SEATTLE — Nov. 5, 2002 — The research sheds new light on the cancer-fighting mechanisms of PC-SPES, an herbal supplement taken by men with advanced prostate cancer to slow the progression of their disease. "PC" stands for prostate cancer; "SPES" is Latin for hope. Peter Nelson, M.D., an associate member of Fred Hutchinson's Human Biology and Clinical Research divisions and an associate professor of medicine at the University of Washington, led the research. Michael J. Bonham, a graduate student in Nelson's lab, was first author on the paper.

While PC-SPES has long been known to act as an estrogen, blocking male hormones that fuel prostate cancer, the researchers found that it also effectively thwarts cancer growth by inhibiting the assembly of specific structural components within prostate-cancer cells, killing the cells and blocking tumor growth. The researchers also found that the supplement contains compounds that behave much differently from estrogens. More research is needed to identify these compounds and understand how they work.

Just as PC-SPES blocks the assembly of structural components that provide support for a cancer cell, several traditional chemotherapy agents, such as Taxol, work in the opposite way by inhibiting the breakdown of the same components. Either way, the cell dies. The researchers found that while PC-SPES and Taxol effectively kill cancer cells independently, the drugs are less effective when combined. They act against each other, which could decrease the effectiveness of therapy.

Funded by CaP CURE and the National Cancer Institute, the research was laboratory-based; it is unknown whether the results would translate to humans. For the study the researchers analyzed the interaction of PC-SPES extracts and Taxol on human prostate-cancer cells that had been grafted into mice.

PC-SPES, a Chinese dietary supplement consisting of eight herbs, in February was voluntarily recalled by its manufacturer, BotanicLab, due to concerns that it was tainted with undeclared prescription-drug ingredients such as DES (an estrogenic agent) and coumadin, a blood-thinning agent.

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Kristen Woodward
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Fred Hutchinson Cancer Research Center
The Fred Hutchinson Cancer Research Center, home of two Nobel Prize laureates, is an independent, nonprofit research institution dedicated to the development and advancement of biomedical technology to eliminate cancer and other potentially fatal diseases. Fred Hutchinson receives more funding from the National Institutes of Health than any other independent U.S. research center. Recognized internationally for its pioneering work in bone-marrow transplantation, the center's four scientific divisions collaborate to form a unique environment for conducting basic and applied science. Fred Hutchinson, in collaboration with its clinical and research partners, the University of Washington Academic Medical Center and Children's Hospital and Regional Medical Center, is the only National Cancer Institute-designated comprehensive cancer center in the Pacific Northwest and is one of 38 nationwide. For more information, visit the center's Web site at www.fhcrc.org.

Fred Hutchinson Cancer Research Center is a world leader in research to prevent, detect and treat cancer and other life-threatening diseases.