Colorectal Cancer Awareness: Decreasing Risks

March is Colorectal Cancer awareness month. To help raise awareness of this condition, we will be sharing guest blogs by gastroenterologist Dennis J. Ahnen M.D., AGAF, FACG of Gastroenterology of the Rockies.

What can you do to decrease your colorectal cancer risk?

Colorectal cancer (CRC) burden is decreasing progressively in the U.S. but it is still the third most common cancer and the second most common cause of cancer death in the United States (taking men and women together). The good news is that both the number of new CRC cases and the number of CRC deaths has decreased by over 40 percent in the last several decades. These decreases are due to beneficial changes in some of the modifiable CRC risk factors and, importantly, by increasing rates for CRC screening.

Risk Factors for Colorectal Cancer

Some of the important CRC risk factors are not modifiable and others are lifestyle factors that can be modified.

Non-modifiable risk factors include:

• Country of origin: Developed countries like the U.S. have a higher risk than developing countries like most of Africa.
• Race/ethnicity/income: CRC risk is higher in African Americans, Alaska Natives and American Indians than in Caucasians or Hispanics, as well as in low-income groups. These differences may be due, at least in part, to different risk factor profiles between the groups and differential access to screening and state of the art treatment.
• Age: CRC is uncommon before age 40, then the risk doubles every decade or until age 80. This is why recommendations are to start CRC screening by age 45 or 50 in otherwise average-risk people.
• Family history: This is a very important risk factor for CRC. Individuals with one or more close relatives (parents, siblings, and children) with CRC are at an increased risk for the disease and should discuss screening with their providers well before age 40. Screening should be started at age 40 or earlier in some of these individuals.

Although you cannot change these risk factors, knowledge of them allows for individualized CRC screening measures.

Modifiable risk factors include:

• Smoking: Cigarette smoking is a cause of CRC, as well as many other cancers.
• Alcohol: Excess alcohol (an average of >1 drink per day for women, >2 per day for men) increases CRC risk.
• Obesity: Being overweight is associated with an increased CRC risk in both men and women.
• Lack of physical activity: Regular exercise (30-60 minutes of vigorous activity 3-4 times per week) is strongly associated with protection from CRC.
• Diet: Diets high in red or processed meat, low in fruits and vegetables and low in high-fiber foods are associated with an increased CRC risk. Vitamin supplements have not been shown to decrease CRC risk.

Each of these modifiable factors is associated with a modest (20-30 percent) effect on CRC risk but the single most important CRC risk factor is a failure to be screened. Regular colorectal cancer screening can decrease risk by up to 70 percent. CRC screening recommendations vary by risk status. Average risk individuals are those with no personal or family history of CRC or precancerous colonic polyp and no inflammatory bowel disease.

Screening Strategies

For those with an average risk, current guidelines recommend starting CRC screening by age 45 or 50 (current guidelines vary on starting age) and continuing until age 75-85 (individualized on basis of risk and health status) for average-risk individuals with any one of several effective screening strategies.

Screening Strategy and Interval if Negative:

• Colonoscopy: Every 10 years
• CT Colonography (virtual colonoscopy): Every 5 years
• Flexible Sigmoidoscopy: Every 5 years
• Combined DNA and fecal immunochemical test (FIT): Every 3 years (ColoGuard is currently approved in the US)
• High-Sensitivity Fecal Occult Blood Test: Annually (FIT or high sensitivity guaiac test)

The best CRC screening test is the one suited to your risk and the one that actually gets done. Colonoscopy is the only one-step screening strategy. If any of the non-colonoscopy screening tests are positive, a colonoscopy needs to be performed in order to identify polyps and cancers in the entire colon, biopsy lesions that are suspicious for CRC and remove colonic polyps which can prevent CRC from occurring.

High-risk populations, such as individuals with a first degree relative with CRC or large (larger than a dime) precancerous polyps, should discuss their family history with their provider and start CRC screening with colonoscopy every five years by age 40 or earlier if the family history of CRC is very strong.

Individuals with inflammatory bowel disease typically are advised to get a colonoscopy with biopsies of the colon every 1-2 years after about 8-10 years of the disease.

How you can decrease your CRC risk?

• Family History: Know your family history of cancer and make sure your primary care professional is aware of it well before age 40.
• Modify known risk factors: Do not smoke or drink alcohol in excess. Strive to maintain ideal body weight throughout life and to get regular exercise several days per week. Eat a diet high in plant foods, low in meat and avoid processed meat.
• Get screened: Start CRC screening by age 45 or 50 and continue until at least age 75.

Contact Gastroenterology of the Rockies to Schedule an Appointment

If you’d like to learn more about prevention and screening for CRC or wish to schedule an appointment with Dr. Ahnen, please call Gastroenterology of the Rockies at 303-604-5000.