From the Journals

Commentary: Composite risk, not age, is key for timing first colorectal cancer screening



The American Cancer Society’s recent recommendation to lower the age of first screening for colorectal cancer to 45 years does not reflect clear knowledge of risks versus benefits, experts wrote in a recent commentary.

Dr. Thomas Imperiale

“In the big picture, [the question of whether to start screening at 45 versus 50 years] seems relatively unimportant compared with using individual patient risk for advanced neoplasia in practical, feasible models” that are geared toward adherence, efficiency, and cost-efficacy, wrote Thomas F. Imperiale, MD, of Indiana University, Indianapolis, and his associates. The commentary is in the October issue of Clinical Gastroenterology and Hepatology.

Tailoring age of first screening on an individual level, based on other risk factors and patient preferences, might improve uptake and benefit-risk ratios, balance, they argued.

Rates of colorectal cancer in persons under age 50 years rose by about 22% between 2000 and 2013. However, estimates for the most recent birth cohorts have wide confidence intervals, “indicating imprecision and uncertainty that this trend will continue,” the experts wrote. Furthermore, the absolute risk of colorectal cancer among individuals younger than 50 years has risen only slightly, from 5.9 cases per 100,000 population to 7.2 cases per 100,000 population. “[This] small increase in incidence may represent a true increase or could be due to increased use of colonoscopy in general, and specifically, for diagnosis or high-risk screening of first-degree relatives of persons with colorectal cancer,” the experts wrote.

Implementing the new recommendation could detect earlier-stage (curable) colorectal cancer “in a youthful and productive age group that may be sandwiched between raising children and caring for aging parents,” they continued. Earlier detection could reduce mortality and reduce the costs of treating a disease that often exceeds $100,000 per person annually.

However, the recommendation was based on a modeling study that assumed 100% adherence. In reality, uptake among 45- to 49-year-olds might be 15%-20%, and “who actually shows up for screening could make or break this recommendation,” the experts said. If younger individuals who underwent screening tended to have few risk factors for colorectal cancer, then the new recommendation would lead to many false positives and unnecessary colonoscopies, with the associated fallout of emotional harm and wasted health care resources, they added.

Population-level studies have identified age as the strongest predictor of colorectal cancer, but age “does not perform as well” at patient level, the experts said. They emphasized the role of other risk factors, such as male sex, having a first-degree relative with colorectal cancer, high body mass index, metabolic syndrome, cigarette smoking, diet, adherence to screening, and use of aspirin, nonsteroidal anti-inflammatory drugs, and hormone therapy. “The goal for providers and health systems is to determine whether and how to change screening practice and policy, and how to incorporate this new recommendation into practice, a necessarily complex process that requires knowing patient risk, patient preferences, and the long-term balance of benefits and burdens,” they concluded (Clin Gastroenterol Hepatol. 2018 Aug 13. doi: 10.1016/j.cgh.2018.08.023).

Dr. Imperiale and coauthor Charles J. Kahi, MD, MS, had no disclosures. Coauthor Douglas K. Rex, MD, disclosed ties to Aries Pharmaceutical, Cosmo Pharmaceuticals, Boston Scientific, Sebela, Medtronic, EndoAid Ltd, Olympus, Paion, Braintree, and Medivators. He also chairs the U.S. Multi-Society Task Force on Colorectal Cancer.

* This story was updated on 10/16/2018.

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