Screening can often detect colon and rectal (colorectal) cancer early, when it's small, hasn't spread, and might be easier to treat. Additionally, because polyps can take as many as 10 to 15 years to develop into cancer, regular screening can also be an effective method of colon and rectal cancer prevention.
In May of 2018, the American Cancer Society (ACS) changed the age of colorectal screening for individuals at an average risk to age 45. While the number of diagnoses for colorectal cancer for adults aged 55 and over has declined over the last 20 years, a disturbing increase of 51% in colorectal diagnoses has been noted for adults under the age of 50 since 1994 (American Cancer Society, 2018). Furthermore, death rates from colorectal cancer in the younger age group are also rising. Based on these statistics, the ACS funded a modeling study that used the age 45 to begin screening rather than at the age of 50. The ACS found that it is more likely that adults will have more favorable outcomes at the lowered age.
ACS’s new screening recommendation is considered a “qualified recommendation” because the hard-scientific data isn’t yet there. The previous recommendation to begin screening at the age of 50 was considered a “strong recommendation” because the scientific evidence is there to support it. It is important to also know that there is more than one organization that makes cancer screening recommendations including the U.S. Preventative Services Task Force. Additionally, whenever screening recommendations change, it is important for you to check with your insurance provider to see which screening guidelines they use as it may affect which screenings are covered as well as your costs and copays.
Screening tests for colon and rectal cancer are:
- High-sensitivity fecal occult blood tests (FOBT). Both polyps and colon and rectal cancers can bleed, and FOBT checks for tiny amounts of blood in feces (stool) that cannot be seen visually.
- Stool DNA test (FIT-DNA). Cologuard®, the only FDA-approved DNA test, is a multitarget test that detects tiny amounts of blood in the stool (with an immunochemical test similar to FIT) as well as nine DNA biomarkers in three genes that have been found in colon and rectal cancer and precancerous advanced adenomas.
- Sigmoidoscopy. In this test, the rectum and sigmoid colon are examined using a sigmoidoscope, a flexible lighted tube with a lens for viewing and a tool for removing tissue. This instrument is inserted through the anus into the rectum and sigmoid colon as air (or carbon dioxide) is pumped into the colon to expand it so the doctor can see the colon lining more clearly.
- Standard (or optical) colonoscopy. In this test, the rectum and entire colon are examined using a colonoscope, a flexible lighted tube with a lens for viewing and a tool for removing tissue. Like the shorter sigmoidoscope, the colonoscope is inserted through the anus into the rectum and the colon as air (or carbon dioxide) is pumped into the colon to expand it so the doctor can see the colon lining more clearly.
- Virtual colonoscopy. This screening method, also called computed tomographic (CT) colonography, uses special x-ray equipment (a CT scanner) to produce a series of pictures of the colon and the rectum from outside the body. A computer then assembles these pictures into detailed images that can show polyps and other abnormalities. Virtual colonoscopy is less invasive than standard colonoscopy and does not require sedation.
Talking with your doctor can help determine which method of screening is right for you.
If polyps are found during colon and rectal cancer screening, a biopsy may be performed. In a biopsy, the doctor takes a small sample of tissue for testing in a laboratory by a pathologist. Often, the abnormal tissue can be removed during colonoscopy or sigmoidoscopy. If a biopsy is not possible, the doctor may suggest other tests that will help make a diagnosis.
If you have screening test results that suggest colon and rectal cancer or you have symptoms, your doctor must find out whether they are due to cancer or some other cause. To do this, your doctor will ask questions about your personal and family medical history and give you a physical exam.
If your physical exam and test results do not suggest cancer, your doctor may decide that no further tests are needed and no treatment is necessary. However, your doctor may recommend a schedule for checkups.