Colorectal Cancer Screening
What is Colorectal Cancer?
Cancer that begins in the colon is called colon cancer, and cancer that begins in the rectum is called rectal cancer. Cancer that begins in either of these organs may also be called colorectal cancer.
Facts and Figures
In Missouri, colorectal cancer has the second highest incidence and mortality rate among cancers. Around 90% of new colorectal cancer cases occur in people who are 50 or older.
The United States Preventive Services Task Force recommends that adults aged 45 to 75 be screened for colorectal cancer.
The decision to be screened after the age of 75 should be made on an individual basis. Adults older than 75 should talk to a doctor about whether or not screening for colorectal cancer would be beneficial.
People at an increased risk of getting colorectal cancer should talk to a doctor about when to begin screening, which test is appropriate, and how often to get tested.
Colorectal cancer almost always develops from precancerous polyps or abnormal growths in the colon or rectum. Screening tests can find precancerous polyps, so that removal can occur before cancer develops. Screening tests can also find colorectal cancer early, when treatment works best.
Millions of people in the United States are not getting screened as recommended. Those people are missing the chance to prevent colorectal cancer or find it early, when treatment often leads to a cure.
Several screening tests can be used to find polyps or colorectal cancer. The United States Preventive Services Task Force outlines the following colorectal cancer screening methods:
- stool tests,
- flexible sigmoidoscopy,
- colonoscopy, and
- CT colonography.
There is no single “best test” for any person receiving colorectal cancer screening; each test has advantages and disadvantages. A doctor should be consulted about the pros and cons of each test and how often to be tested. Which test to use depends on a variety of factors to consider, including personal preference, a patient’s medical condition, the likelihood that the patient will follow through with getting the test, and what resources are available for testing and follow-up.
It is important that people who are receiving colorectal cancer screening talk to a doctor about which test is appropriate.
Stool tests check the stool, or feces, for signs of cancer. These tests are less invasive and easier to have done, but need to be done more often than other colorectal cancer screening tests.
These tests include the guaiac-based fecal occult blood test, the fecal immunochemical test, and the FIT-DNA test.
The guaiac-based fecal occult blood test, or gFOBT, uses the chemical guaiac to detect blood in the stool. It is done once a year. For this test, a health care provider will send a test kit to the patient. At home, the patient will use a stick or brush to obtain a small amount of stool. The test kit is returned to the doctor or a lab, where the stool samples are checked for the presence of blood.
The fecal immunochemical test, or FIT, uses antibodies to detect blood in the stool. It is also done once a year in the same way as a gFOBT.
The FIT-DNA test, also referred to as the stool DNA test, combines the FIT with a test that detects altered DNA in the stool. For this test, an entire bowel movement is collected and sent to a lab, where it is checked for cancer cells. This is done once every one to three years.
For this test, the doctor puts a short, thin, flexible, lighted tube into the rectum. The doctor checks for polyps or cancer inside the rectum and lower third of the colon. This screening test should be repeated every 5 years, or every 10 years when combined with a yearly FIT test.
A colonoscopy is similar to flexible sigmoidoscopy, except the doctor uses a longer, thin, flexible, lighted tube to check for polyps or cancer inside the rectum and the entire colon, as opposed to just the lower third of the colon. During the test, the doctor can find and remove most polyps and some cancers. Colonoscopy is also used as a follow-up test if anything unusual is found during one of the other screening tests. This test can be repeated once every 10 years for those without an increased risk of developing colorectal cancer.
Computed tomography, or CT, colonography uses x-rays and computers to produce images of the entire colon, which are displayed on a computer screen for the doctor to analyze. This test, also referred to as a virtual colonoscopy, should be repeated every five years.
Colorectal Cancer Prevention
Colorectal cancer prevention involves avoiding risk factors that are known to increase the chance of developing colorectal cancer, as well as implementing actions that have been found to decrease colorectal cancer risk. Some risk factors cannot be controlled, such as age, gender, race or family history. However, there are actions that can be taken to reduce colorectal cancer risk.
Get Routine Screenings
Overall, the most effective way to reduce colorectal cancer risk is to get screened for colorectal cancer routinely, beginning at age 45.
Almost all colorectal cancers begin as precancerous polyps, or abnormal growths in the colon or rectum. Such polyps can be present in the colon for years before invasive cancer develops. They may not cause any symptoms, especially early on.
Colorectal cancer screening can find precancerous polyps so that removal can occur before cancer develops. In this way, colorectal cancer is prevented.
Screening can also find colorectal cancer early, when there is a greater chance that treatment will be most effective and lead to a cure.
Limit Alcohol Consumption
Drinking three or more alcoholic beverages per day increases the risk of colorectal cancer. Drinking alcohol is also linked to the risk of forming large colorectal adenomas, or benign tumors that could become cancerous.
Maintain a Healthy Diet
Research is currently being done to find out if diet changes can reduce colorectal cancer risk. A diet low in animal fats and high in fruits, vegetables, and whole grains is recommended by most health professionals to reduce the risk of other chronic diseases, such as coronary artery disease and diabetes.
Increase Physical Activity
A lifestyle that includes regular physical activity is linked to a decreased risk of colorectal cancer.
Cigarette smoking is linked to an increased risk of developing colorectal cancer and death from the disease. Smoking cigarettes is also linked to an increased risk of forming colorectal adenomas, or precancerous polyps. Cigarette smokers who have had surgery to remove colorectal adenomas are at an increased risk for these types of polyps to return.
Tobacco smoke has at least 70 chemicals that cause cancer, also known as carcinogens. Every time tobacco smoke is inhaled, those chemicals get into the bloodstream, which carries them to all parts of the body. Many of these chemicals can damage DNA, which controls how the body makes new cells and directs each kind of cell to do what it is meant to do. Damaged DNA can make cells grow differently. These unusual cells can turn into cancer.
Colorectal Cancer Prevention Resources
The Missouri Tobacco Quitline can help current smokers quit by assigning registered participants with a trained quit coach to make a plan to stop smoking. The Quitline can be accessed by dialing 1-800-QUIT-NOW or at https://quitnow.net/Missouri.
Studies have shown that taking aspirin lowers the risk of colorectal cancer and the risk of death from colorectal cancer. The decrease in risk begins 10 to 20 years after patients start taking aspirin.
Daily aspirin use does come with potential harms, however, including an increased risk of stroke and bleeding in the stomach and intestines. These risks may be greater among the elderly, men, and those with conditions linked to a higher than normal risk of bleeding.
Combination Hormone Replacement Therapy
Studies have shown that combination hormone replacement therapy (HRT) that includes both estrogen and progestin lowers the risk of invasive colorectal cancer in postmenopausal women.
However, in women who take combination HRT and do develop colorectal cancer, the disease is more likely to be advanced when it is diagnosed and the risk of dying from colorectal cancer is not decreased.
There are possible harms of combination HRT including an increased risk of having breast cancer, heart disease, or blood clots.
Family Health History
A doctor may consider a patient’s family health history when deciding which colorectal cancer screening might be appropriate. For example, if a patient is found to have a close family member who had colorectal cancer at a young age or has multiple close family members with colorectal cancer, a doctor may recommend the following:
- starting colorectal cancer screening at a younger age;
- getting more frequent screenings;
- using colonoscopy only instead of other tests; and
- in some cases, sending the patient for genetic counseling.
The genetic counselor may recommend genetic testing based on family health history. When collecting family health history, it is important to include close relatives: parents, brothers, sisters, children, grandparents, aunts, uncles, nieces, and nephews. Any cancers that each relative had and at what age he or she was diagnosed should be listed. For relatives who have died, age and cause of death should be noted.
In some cases, colorectal cancer is caused by an inherited genetic condition called Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer or HNPCC. About 3% (1 in 30) of colorectal cancer cases are due to Lynch syndrome. People with Lynch syndrome are much more likely to develop colorectal cancer, especially at a younger age (before 50), and women with Lynch syndrome are much more likely to get endometrial, or uterine, cancer. People with Lynch syndrome also have an increased chance of getting other cancers, including ovarian, stomach, liver, kidney, brain, and skin cancer. In those who are found to have Lynch syndrome, a doctor can recommend steps to reduce risk of getting cancer in the future or to find it early.
Lynch syndrome is hereditary, meaning that it is caused by inherited genetic changes, or mutations, that can be passed from parents to children. Parents, children, sisters, and brothers of an affected person have a 50% chance of having this condition. Other close relatives are also at increased risk of having Lynch syndrome.
After surgery to remove colorectal cancer, tumor tissue samples are often screened to see if the tumor could have been caused by Lynch syndrome. In some cases, additional testing is needed to know for sure if the tumor was caused by Lynch syndrome. In some cases, endometrial, or uterine, tumors are checked. Genetic counseling and testing for Lynch syndrome also might be recommended if a patient is found to have:
- been diagnosed with colorectal cancer in the past;
- been diagnosed with endometrial cancer (especially before age 50);
- had several family members with colorectal or other cancers related to Lynch syndrome; or
- had a family member with Lynch syndrome.
It is important for those who have been diagnosed with Lynch syndrome to talk to a doctor about an increased chance of getting other cancers caused by Lynch syndrome. Additional regular screening to check for these cancers as well as other actions that can be taken to prevent cancer may be recommended. It is also important to let family members know about a Lynch syndrome diagnosis. Once a mutation that causes Lynch syndrome is found in one person in a family, other family members can then be tested for the same mutation to find out if they have Lynch syndrome and are at an increased risk for colorectal (and other) cancer.
Educational Tools & Resources
Colorectal Cancer Screening Education Campaign
It is important for men and women who are 45 years old or older to get screened for colorectal cancer regularly. Screening tests help find precancerous polyps (abnormal growths) so they can be removed before they turn into cancer. This prevents colorectal cancer. Screening also can find this cancer early, when treatment works best. But about one-third of adults who are 50 years old or older (about 22 million people)—the age group at greatest risk of getting colorectal cancer—have not been screened as recommended.
Public Service Announcements - Radio*
Public Service Announcements - Social Media Video Clips*
- Jimmy Smits: The Screening (:40)
- Jimmy Smits: The Screening (:20)
- This is Personal (:30)
- Diane Keaton: Get Screened (:15)
- Diane Keaton: Get Screened (:30)
Public Service Announcements - Telephone System On-Hold Messaging
- Colorectal Cancer Awareness Month On-Hold Message
- On-Hold Message Script:
March is Colorectal Cancer Awareness Month. Among cancers that affect both men and women, colorectal cancer is the second leading cancer killer in the U.S.
But it doesn’t have to be. Colon cancer can be prevented. Screening for colorectal cancer beginning at age 45 saves lives! Talk to your health care provider today about which screening test is right for you.
Public Service Announcements - Print*
Available to order free for use to educate on the importance of routine colorectal cancer screening.
* Materials developed by the Centers for Disease Control and Prevention’s Screen for Life Campaign. For more Screen for Life: National Colorectal Cancer Action Campaign information, visit cdc.gov/cancer/colorectal/sfl/index.htm.
Note: Feel free to share - be aware that Screen for Life tools are copyrighted and cannot be modified in any way.
Sources / Resources
- Colorectal Cancer
- Colorectal Cancer Prevention
- Colorectal Cancer Screening
- Colorectal Cancer: Screening
- Missouri Information for Community Assessment
- What is Lynch Syndrome and Why is it Important to Know if You Have it?
- What Can I Do to Reduce My Risk of Colorectal Cancer?
- What Should I Know About Screening?