In spring 2001, Perspectives visited the lab of physiologist Laura Murphy to report on cancer research involving ginseng. Three years later, that work still looks promising.

Murphy and her students had found that a water extract of American ginseng slowed down the growth of human breast and prostate cancer cells in culture. They also had discovered that female mice injected with human breast cancer cells develop much smaller tumors if their drinking water is laced with ginseng. (Because these mice are immunosuppressed, they can't fight off the cancer themselves.)

Since then, Murphy's lab has tested the effects of ginseng on breast cancer cells resistant to chemotherapy drugs, including hormone therapies like Tamoxifen. "Cancer in general is pretty bad about developing resistance [to drug therapy]," says Murphy. "Cancer cells develop resistance to different drugs through different means, but regardless of the mechanism, we're able to inhibit proliferation of these cells with ginseng."

A $150,000 grant from the Penny Severns Breast and Cervical Cancer Fund through the Illinois Department of Public Health is funding these studies. And a new, $300,000 National Cancer Institute grant will allow Murphy to study the effect on cancer cell cultures of ginseng co-administered with various chemotherapy drugs. In early experiments, she has found "much greater inhibition of cell growth" with the combination than with either compound alone.

She's already begun following up those findings with animal studies.

"We've given subtherapeutic doses of ginseng and of cancer drugs to immunosuppressed mice that we inoculated with human breast cancer cells," she says. "Individually, these are doses at which we would not expect to see a therapeutic response. But when you give them together, it seems to prevent the cancer from growing."

These animal studies are treating cancer at a very early stage, although the cells themselves are from advanced metastatic human cancers. "We want to look at full-blown cancer in the near future," Murphy says. The goal of the NCI grant is to lay the groundwork for studies in humans.

Some retrospective research studies, most done in Korea, indicate that people who consume a lot of ginseng as part of their normal diet have a lower incidence of cancer. Such dietary consumption appears to be safe. But Murphy cautions against people self-dosing with supplements, which may be adulterated or ineffective and can interfere with other drugs.

There are some 20-25 active compounds in ginseng. Murphy would like to test all of them, determine which ones maximally inhibit cancer cell growth, and combine them to get "a potent anti-cancer cocktail."

Will ginseng fulfill its promise for human cancer patients? Much work remains before the answer is known. Murphy is optimistic, however.

"This is some really exciting stuff," she says.

--Marilyn Davis

> Spring 2004 cover story on cancer research

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