1. Colorectal (Colon) Cancer Slideshow Pictures
2. Digestive Disease Myths Slideshow Pictures

Medical Author:

Dennis Lee, MD

Dennis Lee, MD

Dr. Lee was born in Shanghai, China, and received his college and medical training in the United States. He is fluent in English and three Chinese dialects. He graduated with chemistry departmental honors from Harvey Mudd College. He was appointed president of AOA society at UCLA School of Medicine. He underwent internal medicine residency and gastroenterology fellowship training at Cedars Sinai Medical Center.

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Medical Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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In this Article

• Introduction to colon cancer prevention
• What measures to prevent colo-rectal cancer have proven effectiveness and long term safety?
• What measures to prevent colo-rectal cancer probably are effective but may have long term adverse side effects?
• What measures to prevent colo-rectal cancer probably are effective and safe?
• What prevention measures have been found to be ineffective?
• What about genetic testing for colon cancer?
• Who should consider genetic counseling and testing?
• Why is genetic counseling and testing important in hereditary colon cancer syndromes?
• What can be done now to prevent colorectal cancer?
• Find a local Gastroenterologist in your town
• Colon Cancer Prevention Index

What measures to prevent colo-rectal cancer probably are effective and safe?

Oral supplements of calcium and folic acid, diets high in fruits and vegetables and low in saturated fat and red meat, avoiding obesity, regular exercise, and quitting cigarette smoking are safe measures that probably prevent colo-rectal cancer.

Calcium supplements have been shown in animal and human studies to decrease the number of pre-cancerous polyps. Fruits and vegetables contain many chemicals that inactivate cancer-causing chemicals (carcinogens). Obesity, a sedentary life style, cigarette smoking, and high red meat consumption have been linked to an increased risk of colo-rectal cancer. In a large study of nurses, those who took multivitamins that contained folic acid for decades had less colo-rectal cancer than women who did not take multivitamins.

These measures are considered only "probably" effective because long-term, large-scale, properly designed clinical trials have yet to be performed to establish conclusively that these measures actually prevent colo-rectal cancer.

Doctors are willing to prescribe an agent without conclusive proof of its effectiveness as long as it is safe. In many instances, conclusive proof may be many years away.

What prevention measures have been found to be ineffective?

Anti-oxidants are believed to have anti-cancer effects, but clinical trials using the anti-oxidant vitamins C and A have shown no benefit in preventing colo-rectal cancer.

Many agents or measures that are promising because they have theoretical benefits fall short of expectations when subjected to rigorous clinical trials.