Colorectal cancer is common, deadly and highly treatable if detected early.
Aside from skin cancers, “colorectal cancer is the third most common cancer diagnosed in both men and women in the United States,” according to the American Cancer Society. It’s also the third-leading cause of deaths associated with cancer in men and women, according to the American Cancer Society. In 2021, colorectal cancer is expected to cause about 52,980 deaths, according to the ACS.
These are the ACS estimates for the number of colorectal cancers that will be diagnosed in the U.S. in 2021, for both men and women:
- 104,270 new cases of colon cancer.
- 45,230 new cases of rectal cancer.
How Colorectal Cancer Develops
Colon cancer starts from small growths, called polyps, which develop in the lining of the colon or rectum, says Dr. Emre Gorgun, colorectal surgeon and section chief of Colorectal Surgical Oncology at Cleveland Clinic.
“Over time, some of those polyps can become cancerous,” Gorgun says. “Getting regular and recommended colorectal cancer screenings can help decrease the risk of developing colorectal cancer.”
Early Detection Is Key
“If caught at an early stage, colorectal cancer is not only highly treatable, but curable in many instances, highlighting the importance of routine health maintenance,” Ahn says. That means screening.
Who Should Get Screened for Colorectal Cancer?
Men and women should begin regular screening for colorectal cancer beginning at age 50, according to the U.S. Preventive Services Task Force. Colonoscopies are typically scheduled every five years; ask your health care provider how often you should be screened. Your physician may recommend you get screened sooner if you have a family history of colorectal cancer.
According to the U.S. Centers for Disease Control and Prevention, you should be screened before age 50 if:
If you’re in good health and have a life expectancy of more than 10 years, recommendations call for regular colorectal cancer screening through age 75.
Such screening should be done on a case-by-case basis after age 75, says Dorothy Dulko, a faculty member for the Master of Science in Nursing program at Walden University, an accredited online university headquartered in Minneapolis.
Adults ages 76 to 85 should ask their health care provider if they should be screened, the Task Force recommends. Because colon cancer tends to advance slowly, screening for people past age 75 is typically not recommended. Research published in the British Medical Bulletin in 2018 found that screening for colorectal cancer beyond age 75 is “unlikely to significantly improve life expectancy.”
Colorectal Cancer Screening Options
There are a number of colorectal cancer screening options, which include:
- Flexible sigmoidoscopy.
- Noninvasive home screening tests.
- CT colonography.
Colonoscopy. For generations, a colonoscopy – an invasive procedure in which a physician inserts a long, flexible tube outfitted with a small video camera into the rectum to search for abnormalities or changes in the rectum – has been widely considered the most reliable way to detect signs of colorectal cancer early. A colonoscopy allows a doctor to examine the inside of the entire colon and detect abnormalities like possibly cancerous polyps. The patient is under anesthesia for this procedure. To undergo a colonoscopy, your colon has to be clean. That means you have to prepare the night before the procedure by consuming a bowel-cleaning prescription liquid. You are typically not allowed to eat or consume anything solid the day before the procedure.
“A colonoscopy is the best tool to reduce your cancer risk because the procedure detects cancer and it can also help prevent cancer by allowing the health care provider to find polyps and remove them before they turn into cancer,” Gorgun says.
Flexible sigmoidoscopy. Similar to the colonoscopy, a flexible sigmoidoscopy is a screening procedure used to examine the lower part of the large intestine, or colon, according to the Mayo Clinic. During this procedure, a thin and flexible tube – a sigmoidoscope – is inserted into the rectum. Health care providers use a small video camera at the tip of the sigmoidoscope to “view the inside of the rectum, the sigmoid colon and most of the descending colon – just under the last two feet of the large intestine,” according to the Mayo Clinic. This procedure does not allow the examining physician to see the entire colon. That means this procedure alone “can’t detect cancer or small clumps of cells that could develop into cancer (polyps) farther into the colon.”
Noninvasive home screening tests. In addition to these procedures, which are done by health care providers in a medical office, there are at-home tests you can do to detect colorectal cancer by collecting samples of your own stool. You send the samples to a lab for analysis of the presence of occult or hidden blood in the stool, which could be a warning sign for rectal or colon cancer.
There are three at-home stool sample tests that are currently approved by the Food and Drug Administration, according to Harvard Health. Unlike a colonoscopy, there is no prep necessary to use these tests.
The three types of at-home colorectal cancer tests are:
- Guaiac FOBT (gFOBT). This test uses a chemical to detect a component of hemoglobin, which is a blood protein in the stool.
- Fecal immunochemical test (FIT) or immunochemical fecal occult blood test (iFOBT). The FIT or iFOBT approach uses antibodies to detect hemoglobin shed by polyps or colorectal cancer.
- Multitarget stool DNA test (FIT-DNA). This exam detects trace amounts of blood and DNA from cancer cells in the stool.
The Guaiac FOBT test is widely available without a prescription, says Dr. Mohammad Abbass, a colorectal surgeon at Northwestern Memorial Hospital in Chicago. Some FIT exams are available over the counter; consult with your physician about their availability and whether it is the right test for you, Abbass says. Ask your health care provider whether you can get a multitarget stool DNA test. For example, Cologuard, a stool DNA test, requires a prescription, according to the company’s website.
There are also tests that provide you an analysis without having to mail your sample to a lab. Some will require a prescription; consult with your physician. An example of such an exam is the Second Generation FIT Colon Cancer Test which provides a kit with a solution to conduct a fecal immunochemical test that, according to the company, is “considered a preferred screening method for colorectal cancer detection by the U.S. Preventive Services Task Force” and other medical organizations. Results will appear in one to three minutes.
Research suggests that at-home tests are generally reliable. For example, a meta-analysis published in the Annals of Internal Medicine found that FITs have “high accuracy, high specificity and moderately high sensitivity” for detection of colorectal cancer.
CT Colonography. This noninvasive procedure is conducted at a medical facility and is often called a “virtual colonoscopy.” Specialized equipment is used to examine the colon for polyps or tumors. This relatively new method may be an alternative for patients who can’t have a standard colonoscopy because of the risk of anesthesia, says Dulko. Some insurance companies may not cover this procedure.
How At-Home Tests Compare to Colonoscopies
At-home, stool-based tests for colorectal cancer are becoming more effective, Gorgun says. Also, research suggests that utilization of noninvasive tests may increase the number of people who participate in colorectal cancer screening, Gorgun says.
However, if an at-home test comes back abnormal, a colonoscopy will be needed to examine the colon, he says. “It is important to emphasize that none of the relatively recent developments of these noninvasive strategies for screening will eliminate the need for colonoscopy,” he says. “Therefore all positive results on non-colonoscopy tests should be followed up with a timely colonoscopy.”
Ahn notes that during the COVID-19 pandemic, it may be difficult for many patients to be seen by a gastroenterologist for a routine surveillance colonoscopy. If you do an at-home test, you don’t have to take the risk of sitting in a waiting room, and it eliminates the risks of anesthesia.
“However, there are drawbacks,” Ahn says. At-home tests may miss precancerous polyps with false negative results. Such exams may also produce false positives.
While a colonoscopy may be the best exam for early detection of colorectal cancer, it may be difficult to schedule one while many medical facilities are curtailing in-person appointments to blunt the spread of the coronavirus, Dulko notes. In March, the Centers for Medicare & Medicaid Services issued a statement that all elective surgeries (which includes colonoscopies) and dental procedures be delayed during the COVID-19 outbreak.
“There is no single best test for every person. Each test has advantages and disadvantages,” Dulko says. “Talk to your physician or nurse practitioner about the pros and cons of each test, and how often to be tested. Which test to use depends on personal preferences, medical conditions, likelihood that you will get the test and resources available for follow-up. The most important thing is to get screened, no matter which test you and your health care provider choose.”