Aug. 18, 2018
Colorectal cancer is the second leading cause of cancer death within the United States. Detection and removal of precursor lesions found during screening and earlier detection can significantly reduce incidence and mortality.
Published in a recent issue of CA: A Cancer Journal for Clinicians, the 2018 American Cancer Society (ACS) guideline is based primarily on colorectal cancer (CRC) incidence rates and data obtained from microsimulation modeling that demonstrate a favorable benefit-to-burden balance of screening adults at average risk beginning at age 45. The past average-risk screening guideline was published in 2008 and recommended beginning screening at age 50.
According to Jonathan A. Leighton, M.D., a gastroenterologist at Mayo Clinic's campus in Arizona, the ACS changed the screening guideline because recent data show that there has been a marked increase in the incidence of CRC in younger and middle-aged populations. Dr. Leighton's research interests include new technologies and techniques for detecting colon polyps and colon cancer.
"We don't know whether reducing the age for screening to 45 will save lives or how cost-effective it is, but that is the reason that the American Cancer Society is recommending it. We will have to see if the other societies also change the age recommendation," says Dr. Leighton.
Because of differences in the type and quality of evidence for average-risk screening in adults younger than 50 years, the recommendation to begin screening at age 45 has been designated as a qualified recommendation by the ACS.
In an open letter to providers nationwide, ACS officials noted that they initially considered whether screening should begin earlier in racial subgroups with higher colorectal cancer incidence. Although the underlying cause is not yet well-understood, the data point to a persistent increase in the incidence among younger adults, leading the group to recommend initiating average-risk screening in U.S. adults age 45 and older.
"Large population-based studies are needed to assess the true incidence of colorectal cancer in populations below 50 years of age," adds Suryakanth (Suryakanth Reddy) R. Gurudu, M.D., a gastroenterologist at Mayo Clinic's campus in Arizona whose practice and research focus includes colon polyps, complex polypectomy and high-risk colorectal cancer syndromes. "I agree with Dr. Leighton's observation that we also need studies to examine the cost-effectiveness of beginning universal screening at 45 years of age," says Dr. Gurudu.
In the meantime, how should clinicians respond to this new guideline? "I think physicians and patients need to discuss this, and through shared decision-making, decide what's the best age to start, and which of the endorsed options is right for them," says Dr. Leighton.
"Physicians should also continue taking a thorough family history to identify high-risk patient families," notes Dr. Gurudu. "Patients with a history of rectal bleeding, iron deficiency anemia and weight loss should be promptly evaluated for colorectal cancer even before 50 years of age."
ACS guidelines recommend screening with either a high-sensitivity stool-based test or a structural (visual) exam, depending on patient preference and test availability. Recommended CRC screening tools and intervals are:
- Fecal immunochemical test (FIT), annually
- High-sensitivity guaiac-based fecal occult blood test (HSgFOBT), annually
- Multitarget stool DNA (MT-sDNA) test, every three years
- Colonoscopy, every 10 years
- CT colonography (CTC), every five years
- Flexible sigmoidoscopy (FS), every five years
Additional ACS recommendations
- All positive results on noncolonoscopy screening tests should be followed up with timely colonoscopy.
- Adults at average risk and in good health with a life expectancy of more than 10 years should continue CRC screening through the age of 75 years.
- For individuals age 76 through 85 years, clinicians should use patient preferences, life expectancy, health status and prior screening history as the basis for screening decisions. Screening should be discouraged for individuals older than 85 years.
For more information
Wolf AMD, et al. Colorectal cancer screening for average-risk adults: 2018 guideline update from the American Cancer Society. CA: A Cancer Journal for Clinicians. 2018;68:250.