Little Benefit for Screening Colonoscopy Over 70

Fran Lowry

October 03, 2016

The benefits of screening colonoscopy in preventing colorectal cancer (CRC) in adults 70 years of age appear scant, and the risks associated with the procedure, although low, increase with age, new research suggests.

The study was published online September 27 in the Annals of Internal Medicine.

The authors conclude that screening colonoscopy may have a modest benefit in preventing CRC in Medicare beneficiaries aged 70 to 74 years, and an even smaller benefit in beneficiaries aged 75 to 79 years, but that the risks for adverse events, although low in younger individuals, increased among older persons.

The National Institutes of Health–funded study was conducted by Xabier Garcia-Albeniz, MD, PhD, from the Department of Epidemiology, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, and colleagues.

"Colonoscopy is expected to reduce CRC mortality by identifying asymptomatic, curable cancer and decrease CRC incidence by detecting and removing precancerous polyps," Dr Garcia-Albeniz and colleagues write.

"However, despite its widespread use in the United States, no randomized, controlled trials of screening colonoscopy have been completed."

The procedure is invasive and requires a thorough large-bowel cleansing and, oftentimes, patient sedation. It is associated with a risk for complications such as bowel perforation.

The US Preventive Services Task Force recommends routine CRC screening with any method, including "less burdensome" methods, such as fecal occult blood testing (FOBT) and sigmoidoscopy, for people 50 to 75 years of age who are at average risk for CRC and suggests that screening decisions be individualized for those aged 76 to 85.

Despite the fact that no randomized, controlled trials of screening colonoscopy have been completed and that ongoing trials do not include people aged 75 years and older, Medicare reimburses screening colonoscopy at any age, the authors point out.

In the current study, Dr Garcia-Albeniz and his group used observational data on 1,355,692 Medicare beneficiaries aged 70 to 79 who were enrolled from 2004 to 2012.

Participants had no history of CRC, adenoma, inflammatory bowel disease, or colectomy and had not undergone colonoscopy, sigmoidoscopy, or FOBT within the past 5 years.

They used these observational data to emulate a target trial of colonoscopy screening vs no screening and to measure the 8-year risk for CRC and the 30-day risk for adverse events.

Among people aged 70 to 74 years, the 8-year risk for CRC was 2.19% (95% confidence interval [CI], 2.00% to 2.37%) for those who received screening colonoscopy and 2.62% (95% CI, 2.56% to 2.67%) for those who received no screening.

The absolute risk difference was -0.42% (95% CI, -0.24% to -0.63%).

Among people aged 75 to 79 years, the 8-year risk for CRC was 2.84% (95% CI, 2.54% to 3.13%) for those who received screening colonoscopy and 2.97% (95% CI, 2.92% to 3.03%) for those who received no screening.

The absolute risk difference was -0.14% (95% CI, -0.41% to 0.16%).

The risk for adverse events with colonoscopy increased with age.

Among the 70- to 74-year-olds in the colonoscopy group, the excess 30-day risk for any adverse event was 5.6 events per 1000 individuals (95% CI, 4.4 - 6.8).

Among 75- to 79-year-olds, it was 10.3 per 1000 patients (95% CI, 8.6 - 11.1).

"Our estimates of the effect of screening colonoscopy on CRC incidence and complication rates in older persons are particularly important in view of current policies to increase screening uptake," the authors write.

The study provides "precise estimates of the effectiveness and safety of screening colonoscopy in persons aged 70 and older, an underrepresented population in randomized trials," they comment.

The findings "suggest a modest benefit of screening colonoscopy for preventing CRC in persons aged 70 to 74 years and a smaller (if any) benefit in those who are older.... Our findings may help patients, physicians, and policymakers make informed decisions about CRC screening."

The study was funded by the National Institutes of Health. The authors report no relevant financial relationships.

Ann Intern Med. Published online September 27, 2016. Abstract

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