By LEE BOWMAN
Scripps Howard News Service
April 06, 2006
But a separate review of studies evaluating the use of soy supplements against breast cancer finds the evidence of benefit slight.
The ginger and chili-pepper studies were presented Tuesday during the annual meeting of the American Association for Cancer Research in Washington.
Researchers at the University of Pittsburgh did the chili-pepper study, working with mice to show that capsaicin, the active "hot" ingredient in the pepper, causes pancreatic cancer cells to die through the body's normal process for clearing defective cells.
"We discovered that capsaicin fed orally to mice with human pancreatic tumors was an extremely effective inhibitor of the cancer process, inducing apoptosis (natural cell death) in cancer cells," said Sanjay Srivastava, an assistant professor of pharmacology at Pitt and lead author of the study.
Tumors treated with capsaicin were half the size of tumors found in mice that were treated with saline solution by the end of the study.
The ginger study, done by scientists at the University of Michigan Comprehensive Cancer Center, tested powdered ginger against ovarian-cancer-cell cultures in a lab. Mouse studies are the next step.
The research found that ginger caused cell death in all the ovarian-cancer cell lines tested. Moreover, the spice caused cancer cells to be destroyed both through the normal cell-death process and through another mechanism that involves the cells digesting themselves from the inside out.
The second mechanism is important, because it might offer a way around the difficult tendency of ovarian cancer cells to become resistant to conventional chemotherapy, said Dr. Rebecca Liu, an assistant professor of obstetrics and gynecology at the UM Medical School and author of the study.
Ginger is known to be effective at controlling inflammation, and inflammation contributes to the development of ovarian cancer cells. By halting the inflammatory reaction, the researchers suggest, ginger also stops cancer cells from growing.
"We found that ginger induced cell death at a similar or better rate than platinum-based chemotherapy drugs used to treat ovarian cancer," said Dr. Jennifer Rhode, an oncology fellow and co-author of the study.
But in a study published Wednesday in the Journal of the National Cancer Institute, researchers say that while soy intake may be associated with a small reduction in the risk of breast cancer, the evidence is too weak to recommend widespread use of supplements.
The soy connection has been widely debated and tested for nearly three decades since scientists first noted that Asian women have much lower breast-cancer rates than women in Western nations, yet when Asian women move to the United States, their breast-cancer rates increase. The assumption was that the key lay in the diet, and particularly in consumption of soy products that contain large amounts of hormone-like compounds that affect biological pathways that can alter breast-cancer risk.
Scientists at Johns Hopkins University and Georgetown University pooled the results of 18 studies published between 1978 and 2004 that looked at the association between soy intake and breast-cancer risk. The studies included women in both Asian and Western countries, but only the more recent studies showed American and other Western women eating much soy.
The researchers found an overall relative reduction in breast-cancer risk for soy-eaters - a modest 14 percent for Caucasian women, but the effect was not statistically significant for Asian women.
"We found that soy-food intake was associated with a reduced breast-cancer risk, but the data are not adequate to provide a clear answer to recommend soy foods to prevent breast cancer," said Leena Hilakivi-Clarke, a professor of oncology at Georgetown's Lombardi Cancer Center.
But because the estrogen-like effects of soy supplements on the development of breast tumors remains uncertain over the long run, the researchers especially warned against women taking high-dose soy supplements. Some short-term studies have suggested that the supplements can change breast-cell growth in a way that increases the risk of cancer.
Since soy products have become increasingly common as additives in many Western foods, as well as more openly prevalent in items like tofu burgers and soy milk, the researchers said future studies of diet need to more carefully measure how much total soy women are eating and then try to see if intake matters to cancer risk.
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