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The Clinical Guidelines Committee of the American College of Physicians (ACP) has issued a guidance statement for physicians on colorectal cancer (CRC) screening for average-risk adults in the general population.

The authors, Amir Qaseem, MD, PhD, MHA, of Thomas Jefferson University in Philadelphia, and colleagues, said the aim was to reconcile the differing recommendations from various organizations.

The main recommendations of the guidance, published in the , were the following:

• All adults ages 50 to 75 of average risk should be screened

• Suggested tests and intervals include: fecal immunochemical testing (FIT) or high-sensitivity guaiac-based fecal occult blood testing (gFOBT) every 2 years, colonoscopy every 10 years, or flexible sigmoidoscopy every 10 years plus FIT every 2 years

• Screening should not be done in average-risk adults older than age 75 or in adults with a life expectancy of less than 10 years

Clinicians should select the CRC screening test in consultation with patients after discussing the benefits, harms, costs, availability, frequency, and patient preferences, the ACP document stated, advising that all stool tests should be done on voided samples rather than on those obtained from digital rectal examination.

Clinicians should perform individualized assessment of risk for CRC in all adults, Qaseem and co-authors said, noting that risk is elevated in individuals with a family history of CRC, long-standing inflammatory bowel disease, genetic syndromes such as familial adenomatous polyposis, or a personal history of previous CRC or adenomatous polyps.

Other risk factors for CRC include male sex and older age. "Although there is some discussion regarding differences by race and ethnicity, it is not clear if these differences can be attributed to racial differences or health disparities and inequity in screening, follow-ups, and treatments," the committee members wrote.

They explained that their conclusions derived from an analysis of national guidelines published in English from June 2014 to May 2018 in the National Guideline Clearinghouse and Guidelines International Network. Three guidelines commonly used in clinical practice were also considered.

Recommendations have varied across groups, ranging from those of the American Cancer Society (ACS) and the American College of Radiology to the U.S. Multi-Society Task Force on Colorectal Cancer and the U.S. Preventive Services Task Force (USPSTF). The current of the USPSTF, for example, advise that all average-risk asymptomatic people be screened from age 50 through age 75 and that select individuals ages 76 to 85 be screened as risk factors and history warrant. Individuals over age 85 should not be screened, the USPSTF advises. The task force also recommends annual FIT or FOBT screening and FIT plus a stool DNA panel (sDNA) every 1 to 3 years.

The relying heavily on randomized trials showing reduced CRC mortality, recommend stool testing every 2 years or flexible sigmoidoscopy every 10 years. There is also a strong recommendation for screening for individuals ages 60 to 74, and a weak recommendation for those 50 to 59.

Recently, an international panel recommended personalized screening in the general population based on a 15-year 3% risk threshold in asymptomatic adults ages 50 to 75.

In terms of differing 10-year screening costs, a concern to many, the ACP committee found the following amounts:

• gFOBT -- annual: $60-$280; biennial: $30-$140

• FIT -- annual: $200; biennial: $100

• Sigmoidoscopy without biopsy every 5 years: $1,430-$6,768

• Colonoscopy every 10 years: $911-$6,946

• Computed tomography (CT) colonography (no contrast) every 5 years: $674-$3,076

• sDNA -- every 3 years: $1,527 (three screenings)

The panel noted that head-to-head trials assessing the comparative effectiveness and harms of different screening methods are still needed, and that two comparing colonoscopy with stool-based tests are underway.

"More research beyond diagnostic accuracy assessment is needed to evaluate the clinical benefits and harms of FIT plus sDNA and especially CT colonography," the committee wrote. "Until then, other screening methods have stronger direct and indirect evidence of clinical effectiveness in reducing CRC mortality." Racial and ethnic disparities, as well as sex differences related to CRC screening and mortality, also need more study, Qaseem and co-authors said.

Unanswered Questions

Writing in a Michael Pignone, MD, MPH, of Dell Medical School of the University of Texas in Austin, said that reconciling the different guidelines based on current data is challenging since several important questions have not been, and likely will not be able to be addressed directly in trials because of the large size of such a study that would be required.

Among the unanswered questions, he said, are the following:

• Which testing strategies should be considered in shared decision-making?

• What is the optimal interval after a negative result on a screening test?

• Should average-risk adults begin screening before age 50?

He also noted that the ACP guidance statement did not address in depth the issue of lowering the starting age to 45, although the ACS has made a qualified recommendation for this, extrapolating from epidemiological evidence of an increasing incidence of CRC in younger middle-age adults.

In terms of cost-effectiveness, Pignone said, economic support a qualified recommendation to adopt an earlier starting age only if the screening rate in persons ages 50 to 75 is already high (i.e., over 80%).

Such analyses "also reinforce the most important point in all of the major guidelines: any recommended form of screening in the 50- to 75-year age range is likely to be very cost-effective (if not cost-saving) compared with no screening and should be strongly encouraged," Pignone wrote. "As we consider how best to proceed at the margins, it is important not to lose sight of the strong consensus supporting screening for this age group."