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What is Chemoprevention?

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Updated August 29, 2012

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

The name itself sounds like a way to prevent getting chemo, and that's not too far from the truth. Chemoprevention for cancer involves the use of chemicals, including man-made chemicals or naturally occurring substances, to reduce the risk of developing cancer. Research studies examine the specific compound within a substance, learn how it may stop cell mutation, and then strive to find out what the safe upper limit (dosage) is for most average human beings. These tests take years, if not decades, to safely complete.

Colon cancer (and every cancer) is formed through a process called carcinogenesis, which is the acquisition of abnormal cell mutations that eventually lead to cancer. Chemoprevention focuses on stopping the carcinogenesis before it leads to cancer. We already know that certain chemicals and natural compounds can do this magic in mice or other laboratory animals; now we are striving to learn if the same results can be safely mimicked in humans.

Can I Get Chemoprevention?

Although many of the chemopreventive substances being studied are natural substances (such as the spice turmeric), they are not without risk and are therefore not appropriate for everyone. Your doctor takes many factors into consideration, including your current health, medical history and your family history of colon cancer or hereditary diseases. Some studies hold promise for the use of non-steroidal anti-inflammatory drugs (NSAIDS), such as Celebrex (celecoxib), to help suppress adenomatous polyp formation in people suffering from familial adenomatous polyposis (FAP).

Dietary Considerations

Many of the substances being studied are things that you may normally eat -– without even knowing about their potential cancer-fighting properties. Based on years of research and statistics, dietary recommendations to reduce cancer risk are formed. The American Cancer Society suggests:

  • Trying to eat at least five servings per day of fruits and vegetables
  • Reducing the amount of red and processed meat you consume
  • Reducing the amount of saturated fats you eat

The downside is that most adults cannot eat and absorb enough of the pure chemopreventive compounds in natural foods to fight cancer through diet alone. Studies aim to find ways to concentrate the natural compound while still keeping it safe to ingest and minimizing unwanted side effects, such as bloating or gas.

Vitamins and Minerals

We already know that a diet rich in vitamins and minerals is essential to life. What we are learning is that some of these vitamins and minerals may have special effects within the colon, such as decreasing the size and amount of colon polyps that could turn cancerous in the future. According to the National Cancer Institute, some popular vitamins and minerals being studied for their chemopreventive effects include:

Phytochemicals

Phytochemicals are naturally occurring compounds in plant foods. These chemicals give the living plant its robust colors and health, and help prevent disease. When we eat plant foods, we are ingesting the phytochemicals, many of which are under investigation for their cancer-fighting properties.

The spice turmeric has a phytochemical compound called curcumin, which is responsible for the bright yellow coloring and potential chemopreventive properties of turmeric. Curcumin is under investigation for its potential to decrease colon polyp formation.

Isothiocyanates are phytochemicals found in the superfoods -- or those foods commonly believed to help fight cancer, including horseradish, cabbage and broccoli. Studies are underway to see if isothiocyanates can help reduce the risk of colon cancer specifically.

Soy isoflavones are the phytochemicals found in soybeans and soy products, such as tofu. These chemicals have received extensive press coverage for their hormone-altering side effects, especially in the arena of breast cancer. Researchers continue to study the effects of soy chemicals in both colorectal and breast cancer.

Polyphenols are the chemicals found in green tea and some herbs. These compounds possess potent antioxidants. Antioxidants play an important role in decreasing the risk of cancer as they help rid the body of free radicals, which are highly reactive molecules produced by routine biologic chemical reactions that can damage DNA when present in excess.

Epidermal Growth Factor Receptors

Epidermal growth factor receptors (EGFR) sit on the surface of your cells. These proteins tell your cell when to divide (multiply or grow). We've learned that by blocking certain EGFRs, a class of drugs called monoclonal antibodies can slow the growth of certain cancers. Scientists are looking for ways to use the EGFRs to block colon cancers before they start.

Man-made Drugs

Sometimes a drug that was originally intended for one purpose ends up having another potentially wonderful effect. For instance, the statin drugs, which are intended to decrease high cholesterol levels, are under investigation for their secondary effect of decreasing the risk of colon cancer in people with FAP. Likewise, the non-steroidal anti-inflammatory drugs (NSAIDS), such as aspirin, may reduce the risk of colon cancer in some people.

Sources:

American Cancer Society. (2006). American Cancer Society's Complete Guide to Colorectal Cancer. Clifton Fields, NE: American Cancer Society.

American Cancer Society. (n.d.). What's New in Colorectal Research and Treatment? Accessed July 25, 2012.

National Cancer Institute. (n.d.). Chemopreventive Agents. Accessed July 25, 2012.

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