The American Cancer Society (ACS) estimates that over 1.7 million Americans will be diagnosed with cancer this year alone; of that number, about 145,600 will have colorectal cancer–or cancer of the colon or rectum. And approximately 51,000 individuals will die of colorectal cancer this year. Since 1970, Colorectal cancer’s mortality rate has been reduced by more than 50%, but the statistics are still concerning. The best way to combat cancer is to catch it early; the ACS splits recommended colorectal cancer screening tests into two categories: stool-based and visual.
Stool-based tests are typically done first since they’re non-invasive procedures and don’t require any special diet or preparation beforehand. However, it’s essential to note that abnormal test results aren’t necessarily signs of cancer or pre-cancerous polyps; they can point to other conditions such as hemorrhoids or ulcers. It’s also important to understand that stool-based tests aren’t everyone’s best option: they’re useful for people who are at average risk. Those who are at average risk don’t have a family history of colorectal cancer, a personal history of polyps, or any other risk factors.
There are two routes stool-based tests take: they either look for blood or genetic changes in your stool.
- Fecal immunochemical tests (FIT) or guaiac-based fecal occult blood tests (gFOBT) look for trace amounts of blood in your stool that could point to the presence of large polyps of even cancer in your colon or rectum. These are take-home tests: patients receive a kit and instructions from their doctors. One caveat, however, is that the tests can’t tell where the blood is coming from, so any abnormal results must be followed up by a colonoscopy. Tests such as FIT and gFOBT should be done annually.
- Stool DNA tests check your stool for genetic changes that are sometimes seen in pre-cancerous growths or even cancer cells themselves; these tests also look for blood in your stool, and are done at home as well.
Visual–aka structural–tests look directly inside your colon and rectum for potentially abnormal areas containing polyps or even cancer; they generally follow abnormal stool-based test results. There are three major visual tests:
- Colonoscopies use a flexible tube outfitted with a tiny camera to glimpse at the colorectal region in its entirety. You’ll have to use heavy-duty laxatives to clear out your colon in preparation for this test, and will likely be sedated during the procedure. Any polyps found along the way may be removed concurrently, and if your test is clear, you won’t need another colonoscopy for a decade!
- Flexible sigmoidoscopies are scans of the colorectal area that create detailed cross-sectional images for physicians to scour for cancer or polyps. While you won’t be sedated for this exam, you’ll need to do bowel prep similar to the routine done in preparation for colonoscopies. This exam is carried out by pumping air into the colorectal region, then using a CT scanner to take images of the area. If a specialist finds something in need of a biopsy, you’ll need a colonoscopy as a follow-up. It’s recommended that this procedure is done once every five years.
- CT colonographies (aka virtual colonoscopies) aren’t as common in the United States, but are similar to colonoscopies. The difference is they only look at a specific area of the colorectal region, and less-intensive bowel prep might be required and individuals are generally not sedated during this test.
The ACS recommends that people 45 and over start talking to their doctors about getting screened for colorectal cancer; however, depending on your risk level, it may be wise to begin rigorous screening at an earlier age.