Colon cancer is cancer that originates in the longest part of the intestine. Colon and rectal cancers -- collectively referred to as colorectal cancers -- are the second leading cause of cancer-related deaths in the United States. The National Cancer Institute indicates a need for developing preventative approaches for colorectal cancer. The search for preventative compounds has generated interest in resveratrol, a plant-derived chemical with anti-oxidant properties.
Colon Cancer Basics
The colon and rectum make up the last part of the digestive tract. Cancers that originate in the colon and rectum are often lumped together as colorectal cancers, since they have common features. Colorectal cancer risk increases significantly in people older than 50. Other risk factors for colon cancer include a personal history of colon cancer, family history of colon cancer, inflammatory bowel disease -- including Crohn's disease and ulcerative colitis -- and in a small fraction of patients, genetic predisposition. Dietary factors also play a role in colorectal cancer risk; a diet rich in fruits, vegetables and with high fiber content is associated with lower colorectal cancer incidence. Surgery, chemotherapy, radiation therapy and targeted therapy with antibodies are used to treat colon cancers.
Resveratrol Basics
Resveratrol is a chemical found in the skin of grapes, berries of the Vaccinum species and peanuts. It is part of the disease-defense system in plants and is made when plants are subjected to stresses like infections or injuries. Red wine and red or purple grape juices are sources of resveratrol. Extracts of red grapes or red wine containing resveratrol are also available as dietary supplements. The dosages of resveratrol for use in cancer and other diseases have not yet been established. Consult with your doctor before changing your dietary habits or taking resveratrol supplements.
Colon Cancer-specific Effects
Understanding of the effect of resveratrol on cancer in humans is still in its infancy. Most studies have examined its effects on cancer-derived cells cultured in the lab and in model animals in which cancer is induced by genetic mutations or chemicals, or both. Many types of human cancer cells stop growing, turn off inflammation-promoting processes and undergo apoptosis -- a kind of cell death -- when treated with resveratrol. In addition, resveratrol inhibits tumor growth, formation of new blood vessels and tumor metastases and it shrinks tumors in mice and rats with colon cancers.
Resveratrol also inhibits a network of proteins called the Wnt pathway in colon cancer cells. Genetic mutations that aberrantly activate the Wnt pathway are found in over eighty percent of sporadic colorectal cancers. Resveratrol also dampens inflammation by inhibiting the production of cyclooxygenase-2 -- an inflammation-promoting protein made in larger amounts in colon cancers.
Clinical Studies
The effect of resveratrol on human cancer patients is being examined in a handful of clinical studies. Four early stage clinical studies are examining the safety, useful dosage and tumor-specific effects of resveratrol in colon cancer patients.
A study led by doctors at the University of California in Irvine published in 2009 indicated that resveratrol-containing freeze-dried grape powder inhibited the Wnt pathway in normal, but not cancerous colon cells. The Wnt pathway refers to a network of proteins with important roles in development of the embryo. The pathway is named after a group of related proteins called WNTs that bind to other proteins -- receptors -- on the surface of cells. The WNT-receptor coupling results in turning genes on or off, which in turn governs how cells move, acquire specialized functions and die during development. A study including physicians at the University of Michigan Comprehensive Cancer Center is studying the effect of resveratrol on the molecular features and disease progression of early stage surgically removable colorectal cancers. That resveratrol is safe and well-tolerated is encouraging; however, more thorough analyses are required to ascertain its value in cancer prevention and treatment.
References
- National cancer Institute; Colorectal Cancer Prevention
- "Cancer Management and Research"; Anthony V. Nguyen, et al.; April 2009
- Linus Pauling Institute at Oregon State University; Micronutrient Information Center- Resveratrol
- National Institute of Health Registry of Clinical Trials; Resveratrol and Colon Cancer
