乌鸦传媒

Data on colorectal cancer (CRC) screening gathered over the past decade have prompted the American College of Gastroenterology (ACG) to update its guidelines, last issued in 2009.

The new recommendations, published online in the state that screening should start at age 45 for persons of average risk.

"We now know that the risk is higher than we appreciated for people from age 40 onward. Today, a 45-year-old has the same risk as a 50-year-old had 10 years ago," said Aasma Shaukat, MD, MPH, of the University of Minnesota School of Medicine in Minneapolis, in an ACG to the new guidelines.

The update is timely in that 140,000 new cases of CRC are now diagnosed annually in the U.S., she said, with an alarming increase in people younger than 50. The disease is estimated to account for as much as 10% of all cancer deaths.

Screening has changed a lot since 2009, Shaukat noted, and CRC is unique in that there are now seven different screening modalities. Patients have a wealth of choices, ranging from two-step procedures such as guaiac fecal occult blood assays, stool DNA testing, and CT colonography, to one-step diagnosis with colonoscopy.

While the ideal test is safe, non-invasive, accurate, readily available, and inexpensive, "the best test is one that the patient is willing to have and the healthcare system is willing to give," Shaukat said.

Despite the availability of multiple screening modalities and public health initiatives to boost CRC screening, nearly one-third of the eligible U.S. population remains unscreened, the authors noted. "CRC screening rates must be optimized to reach the aspirational target of >80%," they wrote.

And while CRC incidence has declined in those 50 and older, incidence rates have doubled in people ages 20 to 49. It has been estimated that those born around 1990 have twice the risk of colon cancer and quadruple the risk of rectal cancer compared with those born around 1950, the authors noted.

The guidelines, based on varying degrees of evidentiary strength, were formulated in response to several key questions and are intended to reduce the incidence of advanced adenoma, CRC, and related mortality.

Guideline Highlights

Age for starting CRC screening in average-risk men and women should be lowered to 45 from 50, with routine screening still recommended to age 75. Screening beyond age 75 should be individualized to the patient.

African Americans in particular should begin screening at age 45, and special efforts are needed to improve screening rates and reduce disparities in treatment and outcomes. Compared with white patients, incidence rates are 24% higher in Black men and 19% higher in Black women, the authors noted. Stage-adjusted CRC mortality is also disproportionately higher in African Americans, with rates 47% higher in men and 34% higher in women versus their white counterparts.

Screening should be seen as either a one-step process such as colonoscopy, which allows simultaneous diagnosis and treatment, or a two-step process such as stool-based testing followed by colonoscopy if positive.

Colon capsule endoscopy is an option for those unwilling or unable to undergo colonoscopy or fecal immunochemical testing (FIT). If this test is negative, screening may be repeated in 5 years.

For individuals with a family history of CRC or an advanced polyp in one first-degree relative at age <60 years or CRC or an advanced polyp in two or more first-degree relatives at any age, guidelines conditionally suggest initiating colonoscopy at the earlier age of 40 or 10 years before the youngest affected relative (whichever is earlier).

The following intervals should be followed for different screening modalities:

• FIT annually
• Colonoscopy every 10 years
• Multi-target stool DNA test every 3 years
• Flexible sigmoidoscopy every 5 to 10 years
• CT colonography and colon capsule endoscopy every 5 years

A positive multi-target stool DNA test followed by a colonoscopy with no findings should not prompt any further workup, and repeat screening should be offered at 10 years.

The Septin 9 blood test is not recommended for screening.

Endoscopists should measure quality indicators for screening colonoscopy and achieve minimum benchmarks for cecal intubation rates (>95%), adenoma detection rates (>25%), and withdrawal times (>6 minutes). Those with adenoma detection rates of less than 25% should take remedial training.

Colonoscopists should spend at least 6 minutes inspecting the mucosa during scope withdrawal.

In terms of chemoprevention, the guidelines suggest using low-dose aspirin, in addition to CRC screening, in individuals ages 50 to 69 who have a cardiovascular disease risk of at least 10% over the next 10 years, who are not at increased risk for bleeding, and who are willing to take aspirin for at least 10 years to reduce CRC risk.

Organized screening programs should be developed to improve adherence to CRC screening and follow-up of two-stage screening if the first test is positive. This can be improved with patient navigation and reminders, clinician interventions, provider recommendations, and clinical decision support tools.

Shaukat does not expect the new guidelines to stir controversy among gastroenterologists. "But we did recommend against the blood-based test Septin 9 for screening, and there may be pushback against that."

Comment