Prevention and Treatment of Colorectal Cancer by Natural Agents from Mother Nature

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States after cancers of the lung and the breast and/or prostate. Whereas the incidence of CRC in the United States is among the highest in the world (approximately 52/100,000), its incidence in India is among the lowest (approximately 7/100,000), suggesting that lifestyle factors may be involved in development of the disease. Whereas obesity, excessive alcohol consumption, a high-calorie diet, and a lack of physical activity promote this cancer, evidence indicates that foods containing folates, selenium, vitamin D, dietary fiber, garlic, milk, calcium, spices, vegetables, and fruits are protective against CRC in humans. Numerous agents from mother nature (also called nutraceuticals) that have potential to both prevent and treat CRC have been identified. The most significant discoveries relate to such compounds as cardamonin, celastrol, curcumin, deguelin, diosgenin, thymoquinone, tocotrienol, ursolic acid, and zerumbone. Unlike pharmaceutical drugs, these agents modulate multiple targets, including transcription factors, growth factors, tumor cell survival factors, inflammatory pathways, and invasion and angiogenesis linked closely to CRC. We describe the potential of these dietary agents to suppress the growth of human CRC cells in culture and to inhibit tumor growth in animal models. We also describe clinical trials in which these agents have been tested for efficacy in humans. Because of their safety and affordability, these nutraceuticals provide a novel opportunity for treatment of CRC, an old age disease with an age old solution.