Inhibition of Prostate Cancer by Natural Compounds
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Inhibition of Prostate Cancer by Natural Compounds Source: Oregon
Medical Press ompress.com/research-prostate-cancer.htm On this page we explore some of the studies conducted on prostate cancer using natural compounds. Pages for other cancers will be created in the near future. Keep in mind that the information summarized here is only a small part of the total research available on prostate cancer; it is provided only to convey the fact that several studies have been done and that preliminary research suggests that various natural compounds could affect prostate cancer progression. Dozens of human, animal, and test tube studies on prostate cancer are discussed in Natural Compounds in Cancer Therapy. A few of each are summarized below. New studies on prostate cancer and natural compounds are being published regularly. For a brief description of the compounds mentioned, see the introductory ompress.com/research-welcome.htm on the research page. The articles summarized here do not prove that natural compounds effectively treat prostate cancer; many more studies will be needed before proof will be available. However, these studies do point out the promise of natural compounds. Keep in mind that when considering test tube and animal studies it is important to pay attention to the concentrations used and doses given. If the concentration is high enough, thousands of natural compounds will inhibit cancer in the test tube, but this does not mean that they would make good anticancer compounds. Cancer must be inhibited at reasonable concentrations for a compound to look promising. Similarly, it is important to look at the doses used in animal studies—some studies use doses that are far in excess of those that humans could possibly take. Although important, dose information is not discussed in detail in the research summaries on this site; the issues surrounding it require a more detailed explanation than can be given here. However, Natural Compounds in Cancer Therapy does treat this issue in depth. A long list of natural compounds has been reported to inhibit prostate cancer cells in the test tube. These include vitamin D3, the flavonoid apigenin, curcumin (from tumeric), EGCG (from green tea), genistein (from soy), the flavonoid luteolin, the hormone melatonin, the essential oils limonene and perillyl alcohol, the fatty acid EPA (from fish oil), proanthocyanidins (from pine bark and grape pips), PSK (from mushrooms), the flavonoid quercetin, resveratrol (from grapes), vitamin A, and vitamin E. All of these are reviewed in Natural Compounds in Cancer Therapy. Animal studies also report promising results. For example: Oral administration of a genistein isoflavonoid mixture from soy inhibited the growth of transplanted human prostate cancer cells in mice by 30 percent. Angiogenesis (the growth of new blood vessels towards a tumor) was also inhibited (Zhou et al, 1999a). Solid tumors cannot live without active angiogenesis. Injection of the active form of vitamin D3 reduced the growth of transplanted prostate cancer cells in rats (Lokeshwar et al, 1999). Genistein given in the diet inhibited the growth of human prostate cancer cells in mice. A soy isoflavonoid concentrate also inhibited tumor growth (Zhou et al, 1999b). In a study in mice with transplanted human prostate cancer cells, a diet rich in flaxseed oil did not reduce the tumor burden or increase life span, whereas a diet rich in fish oil (EPA) did (Connolly et al, 1997). This suggests that some forms of omega-3 fatty acids may be more potent in cancer treatment than others. Vitamin E reduced the ability of high-fat diets to promote the growth of transplanted human prostate cancer cells in mice (Fleshner et al, 1999) Animal studies also report promising results. For example:
Human studies have also reported that natural compounds can affect prostate cancer or reduce the side effects of chemotherapy or radiotherapy. One combination of natural compounds that deserves mention is PC-SPES, a mixture of extracts from eight herbs. It was designed to treat prostate cancer and appears to act partly through an estrogenic action. It has been tested in several animal and human trials and results suggest that it reduces plasma concentrations of PSA (prostate specific antigen), a tumor marker for prostate cancer, and in some cases reduces tumor burden (de la Taille et al, 2000a, de la Taille et al, 2000b; Small et al, 2000). Side effects are minimal, other than estrogenic reactions, which can be significant. A recent paper explained that the effectiveness of PC-SPES is due to its "complex composition which may target many signal transduction and metabolic pathways simultaneously, thereby eliminating the back-up or redundant mechanisms that otherwise promote cell survival when single-target agents are used" (Darzynkiewicz et al, 2000). This explanation, published in the International Journal of Oncology, supports the hypotheses proposed in Natural Compounds in Cancer Therapy. Other human studies also have been done. For example, twenty-one grams of glutamine (an amino acid) given orally daily increased tumor destruction and improved gut parameters in prostate cancer patients undergoing radiotherapy (Richards et al, 1992). In a study on seven patients with prostate cancer, oral administration of the active form of vitamin D3 reduced the rise in PSA levels in all patients (Gross et al, 1998). The above is only a summary of the many studies that have been done. Importantly, hundreds of other studies have been conducted on other cancers and the data that they provide is often relevant to prostate cancer. As important as studies specific to prostate cancer are, it is also crucial to understand the general mechanisms at play in cancer progression and the means by which these mechanisms can be thwarted. Because many cancers progress using the same mechanisms, compounds that inhibit those mechanisms in one type are likely to do so in others also. This is why, for example, compounds like genistein inhibit a wide variety of cancer types. Hippocrates once said: "Let your food be your medicine and your medicine be your food".
Nutraceuticals and Phytochemicals in Plants Can Fight Cancer
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