Colorectal Cancer Screenings: What You Need to Know
March is National Colorectal Cancer Awareness Month, and that means it’s a perfect time to get the latest information on colorectal cancer screenings. Even though overall rates have been slowly dropping for decades, the American Cancer Society estimates that there will still be nearly 150,000 new cases of colorectal cancer in 2021. This devastating disease is one of the most commonly diagnosed types of cancer, and each year it causes over 50,000 deaths. The evidence also suggests that the mild drop in cases understates the concurrent rise in colorectal cancer among people younger than 50 years old.
In light of this increase in incidences of cancer among young people—and that the drop in cases for older people can be explained by increased screenings—the American Cancer Society, the National Cancer Institute, and the US Preventive Services Task Force (USPSTF) recommend regular colorectal cancer screening tests. As a premier gastroenterology practice, Cary Gastro is a strong advocate for and provider of colonoscopies and other types of colorectal screening. Indeed, overwhelming research continues to show that regular screening is the best and only way to prevent colorectal cancer.
Facts About Colorectal Cancer
The term “colorectal cancer” (CRC) is often used to interchangeably refer to either colon cancer or rectal cancer; they are grouped together because they are closely related in terms of location, progression, and symptoms. In essence, CRC can be defined as an abnormal growth of cells in either the colon or rectum that can potentially spread to other tissues and organs in the body. Like other forms of cancer, CRC involves a mass of cancerous cells that tend to aggressively grow and spread if left untreated. Over time, the metastasized cells can cause widespread cell death and loss of colon function.
Even prior to the development of cancerous cells, the origins of CRC can be found in overgrowths called polyps that form on the inner lining of the colon or rectum. These colorectal polyps are generally benign, but they can become cancerous (usually over many years) if they are left unchecked. There are several categories of polyp characteristics, though some of these characteristics may overlap:
- Adenomatous: Also known more simply as an adenoma, this type of polyp is by far the most common; it is estimated that around 70% of all polyps are adenomatous. Even though only a small percentage of adenomas end up being cancerous, nearly all malignant polyps start as this type. Adenomatous polyps can further be classified into three different growth patterns: tubular, villous, and tubulovillous, though the most common of these is tubular.
- Tubulovillous: Around 15% of polyps detected in a cancer screening are villous or tubulovillous, and the presence of one has a proportionately high risk of becoming cancerous.
- Serrated: This kind of polyp is characterized by its saw-like appearance when viewed under a microscope. The most common version is known as a sessile serrated lesion (SSL), and it is mostly found in the cecum and ascending colon. SSLs are generally regarded as premalignant because of their tendency to lead to cancer, and their flat (sessile) shape make them more difficult to detect.
- Hyperplastic: Hyperplastic polyps are related to serrated polyps in terms of shape, and they are also relatively common. Unlike SSLs and adenomas, hyperplastic polyps have extremely low malignancy potential and are therefore almost always benign.
- Inflammatory: Inflammatory polyps are most often associated with common gastrointestinal conditions like inflammatory bowel disease (IBD), which includes ulcerative colitis and Crohn’s disease. Rather than being a “true” polyp, inflammatory polyps are a direct reaction to chronic inflation and therefore aren’t at risk of developing into cancer.
What Is Involved in a Colorectal Cancer Screening Test?
The fact that colorectal cancer almost exclusively arises from polyps that develop on the wall of the colon or rectum points to the key reason for screening and early detection: the earlier you detect and remove a polyp, the greater the chance of preventing any of those polyps from becoming cancerous. But even if actual cancer is detected during a screening, catching it early is critically important. In fact, according to the American Cancer Society, the five-year survival rate of CRC is 90% when early-stage cancer is detected.
People have been known to avoid CRC screenings over fears of the procedures themselves, but the truth is that the discomfort is actually quite minor. Moreover, the screening recommendations are generally spread out over years, so it isn’t something you have to psych yourself up for very frequently. There are several tests doctors may use, depending on how old you are and some other factors. Generally speaking, though, everyone who opts in for regular screenings should expect one of the following screening options to be conducted every 5-10 years for average-risk people between the ages of 50 and 75 (and as early as 45 for those with increased risk factors):
- Colonoscopy (every 10 years): Perhaps the most well-known test in this group, the colonoscopy involves the use of a colonoscope that is inserted into the rectum. The camera mounted on a flexible tube is used to thoroughly examine the entire colon to search for polyps or any other abnormalities. If small polyps are detected, additional tools on the colonoscope can immediately remove them; larger polyps would be of greater concern and typically require surgery to remove and be subjected to a biopsy.
- Flexible Sigmoidoscopy (every 5 or 10 years): This is a shorter version of a colonoscopy that only examines the sigmoid colon, the lower section of the colon that directly precedes the rectum.
- CT Colonography (every 5 years): Also known as a “virtual colonoscopy,” this test uses multiple X-ray images to create a computed visualization of the colon. The primary benefit of a virtual colonoscopy is that the colonoscope doesn’t need to be used, but the images it produces don’t provide as much detail as a standard colonoscopy; as a result, smaller polyps (less than 10mm in diameter) may not be detected. Additionally, if a polyp is detected, a colonoscopy will still be needed to remove it.
- gFOBT (once a year): Short for “guaiac-based fecal occult blood test,” gFOBT is a stool test that uses a chemical called guaiac to detect blood in stool. This test is a home test kit provided by a doctor; after obtaining a small amount of your stool with the kit, it is sent to a lab to be analyzed. This test is able to detect blood that may not be visibly apparent.
- FIT (once a year): Short for “fecal immunochemical test,” FIT functions in much the same way as gFOBT. Rather than using guaiac, however, the test result relies on the presence of antibodies to detect any blood in the stool.
- FIT-DNA (every 3 years): Known by its trade name, Cologuard, this test requires the collection of a full stool sample to be sent to the lab, and it is used to detect mutated DNA in stool.
It is important to note that there is a fundamental difference between the imaging screening methods and stool tests described above. While the stool tests are legitimately useful to doctors, they are only able to detect blood or cancerous cells. In other words, these tests can only tell you if you already have colorectal cancer. Only a colonoscopy can detect the presence of polyps and provide the opportunity to remove them before they actually become malignant. That is why it’s so crucial to follow the recommendations and get a colonoscopy at the right time. On an insurance-related note, a screening colonoscopy should be covered by insurance; however, a diagnostic colonoscopy that would be required because a stool test showed cancer is often not covered by insurance.
In an effort to make CRC screenings more accessible, some healthcare providers have recommended at-home stool tests as an alternative to a colonoscopy. As noted above, these stool tests are only able to detect cancer that is already present, so they shouldn’t be used as a direct alternative. The only way to truly prevent colorectal cancer is to get regular screenings using some type of colonoscopy so that the gastroenterologist can thoroughly visualize the colon in detail.
“A colonoscopy tests the entire length of the colon, checking all areas for possible colon cancer,” said Dr. Mike Brody, one of Cary Gastro's board-certified gastroenterologists. “It is through this screening that we detect colon cancer and colon polyps, and is the only screening test that allows us to remove the precancerous lesion polyp during our screening exam."
Contact Cary Gastro About Colorectal Cancer Screening
Unlike some other forms of cancer, colorectal cancer is known for taking many years to develop. This fact makes it one of the easier forms of cancer to identify and treat early, often even before the cancer develops. Cary Gastro is dedicated to providing you with excellent digestive health care, and that includes these potentially life-saving cancer screenings. If you are between the ages of 45-50 and haven’t yet had a screening, contact us today to request an appointment. Getting a screening is the quickest and simplest way to make sure that your colon is cancer free!