A large population-based observational study by Xabier García-Albéniz, MD, PhD, of the Harvard T.H. Chan School of Public Health, and colleagues evaluating the effectiveness and safety of screening colonoscopy for the prevention of colorectal cancer in people aged 70 to 74 and 75 to 79 has found the test reaped only a modest benefit in preventing colorectal cancer, especially in the older individuals. The study showed colonoscopy reduced the 8-year risk for colorectal cancer from 2.6% to 2.2% in the younger group and from 3.0% to 2.8% in the older group. The risk for adverse events was low but greater among older persons. The researchers’ findings may help patients, physicians, and policymakers make informed decisions about colorectal cancer screening. The study was published in Annals of Internal Medicine.
The researchers analyzed data from 1,355,692 Medicare beneficiaries (2004–2012) aged 70 to 79 at average risk for colorectal cancer who used Medicare preventive services and had no previous diagnostic or surveillance colonoscopies in the past 5 years. The beneficiaries had no history of colorectal cancer, adenoma, inflammatory bowel disease, or colectomy.
The observational data were used to emulate a target trial with two groups: colonoscopy screening and no screening.
Study Findings
In the beneficiaries aged 70 to 74 years, the 8-year risk for colorectal cancer was 2.19% (95% confidence interval [CI], 2.00%–2.37%) in the screening colonoscopy group and 2.62% (CI, 2.56%–2.67%) in the no-screening group (absolute risk difference, –0.42% [CI = –0.24% to –0.63%]). Among those aged 75 to 79 years, the 8-year risk for colorectal cancer was 2.84% (CI = 2.54%–3.13%) in the screening colonoscopy group and 2.97% (CI = 2.92%–3.03%) in the no-screening group (risk difference, –0.14% [CI = –0.41 to 0.16]).
The excess 30-day risk for any adverse event in the colonoscopy group was 5.6 events per 1,000 individuals (CI = 4.4–6.8) in those aged 70 to 74 and 10.3 per 1,000 (CI = 8.6–11.1) in those aged 75 to 79.
“We provide precise estimates of the effectiveness and safety of screening colonoscopy in persons aged 70 or older, an underrepresented population in randomized trials. Our findings suggest a modest benefit of screening colonoscopy for preventing [colorectal cancer] in persons aged 70 to 74 and a smaller (if any) benefit in those who are older. The risk for adverse events was low in both age groups. Our findings may help patients, physicians, and policymakers make informed decisions about [colorectal cancer] screening,” concluded the researchers.
Funding for this study was provided by the National Institutes of Health.
García-Albéniz X, et al: Ann Intern Med. September 27, 2016 (early release online). ■
