Published:
March 21, 2023
Understanding the age guidelines and various tests to find and prevent colorectal cancer can be confusing. Gastroenterologist Dr. John Betteridge explains what you need to know about these potentially lifesaving colon cancer screenings.
What recent data has led to the shift in the recommended screening age from 50 to 45?
The rate at which people are diagnosed with colon cancer in the U.S. is dropping among people 65 and older but rising in younger age groups. Data from the American Cancer Society showed that in 2020, 12% of colorectal cancer cases occurred in patients younger than 50. Data from the National Cancer Institute showed that from 2014-2018, Americans aged 50 and older saw colon cancer rates drop 2% per year, but Americans under 50 saw a 1.5% yearly rise in colon cancer incidence.
Many people are concerned with costs. Are insurance companies covering all screening options starting at age 45?
Yes. Insurance companies in the Lancaster area have universally adopted age 45 to start CRC screening. This includes Medicare and Medicaid insurance products.
What are the advantages/disadvantages of each screening option? Which one is most effective?
There are multiple excellent options for screening for colon cancer, but they are very different. To understand more about the differences, one needs to remember that virtually all colon cancers follow a well-understood sequence from polyp to adenoma to carcinoma. This means that virtually all colon cancer starts as a benign precancerous polyp.
A good way to think about screening tests is to group them into cancer detection vs. prevention tests. All tests do some of both, but there are real differences in some of the choices. The most common choices in our area are stool-based tests, like Fecal Immunohistochemistry (FIT) or Cologuard, and colonoscopy.
Both Cologuard and FIT test for microscopic amounts of blood in the stool, and Cologuard adds DNA-based tissue screening for intestinal cells that are also sloughed off with stool. Cologuard (90-92%) and FIT (74-86%) are both very good at detecting cancer when present, which allows for early treatment like surgery and/or chemotherapy, resulting in higher cure rates. However, they are poor at detecting large precancerous polyps (42% for Cologuard and 30% for FIT).
Colonoscopy will detect nearly 100% of cancers and more than 95% of large precancerous polyps. This high rate of detection of polyps and removal of these polyps (polypectomy) allows colonoscopy to reduce the risk of a patient ever getting cancer by an estimated 40-75%, obviating the need for cancer treatments.
What drives the recall interval between screening tests? Are certain populations at higher risk and need more frequent screening?
The recommended time between tests is dependent on the quality of the test and also other factors, like family history. In the case of colonoscopy in a patient who has precancerous polyps detected and removed, the size, number and microscopic appearance of the polyps determine the interval to the next colonoscopy. Patients with high-risk conditions like Inflammatory Bowel Disease or a personal history of precancerous polyps or colon cancer are not eligible for stool-based tests. These patients should be screened with colonoscopy and often are screened earlier and more often than the average-risk population.
We have an aging population in Lancaster County. Is there an upper limit age at which we should consider stopping the screening exams?
In general, screening exams become less effective as we age. Patients who have never had cancer or precancerous polyps are not recommended to undergo continued screening beyond age 75. However, higher-risk patients with strong family history or personal history of polyps, for example, may still benefit from continued screening beyond this age, and an individualized decision should be made in concert with their doctor.
Who should I talk to about my options for colon cancer screening?
Your primary care provider can help you understand which screening test is best for you and can order a colonoscopy or in many cases, provide you with an at-home test.