Cancer process promotion

The most convincing data have been obtained from rodent models of cancers that revealed protective effects of curcumin against cancers of aU sites. Curcumin is able to inhibit all steps of cancer processes, initiation, progression, and promotion. These observations, combined with the apparent lack of toxicity of curcumin for doses up to 8 g/day for 3 mo suggest potential uses of curcumin as an anti-carcinogenic chemoprotective agent. ... 

The specific mechanisms by which individual dietary components can alter the cancer process remain poorly understood. However, mechanisms underlying the carcinogenesis process are understood sufficiently so that model systems to evaluate the ability of a specific compound to inhibit or promote processes that may prevent or delay cancer development can be predicted. Phytochemcials can act at a variety of sites relevant to the development of the cancer cells. They may inhibit carcinogen activation, induce hepatic detoxification pathways, exert antioxidant effects/metal chelation properties, enhance immune response, induce apoptosis, and alter hormonal environment. 

A somewhat related situation can be used to explain the well-publicized lung-cancer inducing effects of P-carotene in heavy smokers. This subpopulation will have low vitamin C levels and hence damage due to smoke components, such as N02 can produce P-CAR which will reach the lung and initiate damage. In nonsmokers, the vitamin C (or other water-soluble antioxidant) is likely to be present in sufficient concentration to preclude this damaging process. Indeed, this speculation has been promoted by the American Chemical Society as the subject of a press release in 1997 (Bohm et al. 1997). 

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