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
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.
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 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
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
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 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.