Originally posted on the Daily Progress:
Colorectal cancer (CRC) is the second-most-common cancer in America among men and women combined. It’s also the second leading cause of death from cancer. The American Cancer Society (ACS) estimates there will be 145,600 new cases of colorectal cancer this year, with 3,540 estimated to be diagnosed in Virginia alone.
In patients older than 55, the incidence of colon cancer has been decreasing by roughly 3.7 percent per year. This decrease has been attributed to improved adherence to modern screening methods. Unfortunately, there has been an increase in incidence among patients younger than 55 by 1.8 percent each year. The cause of this increase is unknown, but it has prompted the ACS to modify its recommendation of when colon cancer screening should begin— the ACS now recommends to start screenings at age 45, rather than 50. Currently, major gastroenterology societies have not changed their recommendations to begin screening at age 50.
Researchers have identified many risk factors for colon cancer, including a family history of colon cancer or polyps, older age, male sex, obesity, smoking, alcohol use, and diet (increased red meat consumption with low amount of fruits and vegetables).
Symptoms of colon cancer can include weight loss, change in stooling habits, rectal bleeding, abdominal pain and anemia. However, many individuals may have no symptoms at all, which is why it’s important to have regular screenings.
What is a polyp?
A polyp is a precancerous lesion in the lining of the colon that may lead to colon cancer. Polyps are quite common; they’re found in roughly 30 percent of patients during colonoscopy. Polyps typically do not cause symptoms unless they are very large. Precancerous polyps are characterized through biopsy as either traditional “adenomatous” or sessile (flat) serrated polyps. They can be further subclassified into higher-risk polyps based on size and pathologic features. It is estimated that 70 percent of colon cancer originates from traditional adenomas, and sessile serrated polyps account for the majority of the rest.
The U.S. Preventive Services Task Force updated its recommendations on colon cancer screening in 2016. At that time, it was estimated that a third of Americans had not undergone colon cancer screening. In order to increase adherence, multiple screening methods were proposed.
Most gastroenterologists recommend colonoscopy as the test of choice because it has the highest sensitivity in identifying colon cancer and is the only test that allows for therapeutic removal of polyps, preventing their progression to colon cancer. Colonoscopy is also the only recommended test for individuals with a prior personal history of polyps or a family history of colon cancer.
Stool sample methods are also available and include fecal occult blood test (FOBT), fecal immunochemical test (FIT), and FIT-DNA test (Cologuard). These tests primarily evaluate for colorectal cancer rather than polyps, which rarely bleed. On average, a FIT test will detect 79 percent of colon cancers, and FIT-DNA will detect 92 percent. All positive test results should be followed by a complete colonoscopy. CT colonography and flexible sigmoidoscopy are also potential colon cancer screening methods, but they are less commonly used. Research is being conducted into the potential use of blood tests to screen for colon cancer.
Colorectal cancer is the second most common cause of cancer and cancer-related deaths in America. Screening is recommended starting at age 50, or earlier in high-risk individuals. There are multiple screening methods, but colonoscopy is generally recommended as the initial choice given its high sensitivity and potential to remove precancerous polyps. If you’re 50 or older and have not had a colon cancer screening, talk to your physician.
American Cancer Society. Cancer Facts & Figures 2019. Atlanta: American Cancer Society; 2019.
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Pochapin, Mark B. “2017 Emily Couric Memorial Lecture: Colorectal Cancer: Polyps, Prevention, and Progress.” The American journal of gastroenterology (2018): 1.
Rex, Douglas K., et al. “Colorectal cancer screening: recommendations for physicians and patients from the US Multi-Society Task Force on Colorectal Cancer.” The American journal of gastroenterology 112.7 (2017): 1016.
US Preventive Services Task Force. Screening for Colorectal Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2016; 315(23):2564–2575. doi:10.1001/jama.2016.5989
Dr. Elliott Smith is with Charlottesville Gastroenterology Associates.
This column, which promotes community health, is sponsored by Sentara Martha Jefferson Hospital, Region Ten Community Services Board, Thomas Jefferson Health District and the University of Virginia Health System.