‘Additional preventive’ benefit of colonoscopy for CRC falls short of sigmoidoscopy
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Key takeaways:
- Colonoscopy prevented an estimated 50 CRC cases and 15 deaths per 100,000 person-years compared with usual care.
- The additional benefit of colonoscopy was 12 fewer cases and four fewer deaths vs. sigmoidoscopy.
Colonoscopy screening reduced the incidence of colorectal cancer and related mortality by 30% and 32%, respectively, compared with usual care, although the benefit was less than that of sigmoidoscopy where no screening exists, data showed.
“Sigmoidoscopy and colonoscopy are recommended screening tests for CRC,” Frederik E. Juul, MD, PhD, of the Clinical Effectiveness Research Group at the University of Oslo, and colleagues wrote in JAMA Network Open. “In four large, randomized clinical trials, sigmoidoscopy screening reduced CRC incidence and mortality predominantly in the distal colon and rectum. Colonoscopy has largely replaced sigmoidoscopy for CRC screening. Observational studies suggest that colonoscopy is also associated with reduced proximal colon cancer incidence and mortality.”
They continued: “Data on the effect of colonoscopy screening after longer follow-up are lacking from randomized trials.”
In a comparative effectiveness simulation study, Juul and colleagues pooled data from four randomized clinical trials of sigmoidoscopy screening in Norway, Italy, U.K. and U.S., with at least 15 years of follow-up, and estimated the effectiveness of colonoscopy screening using colonoscopy screening results from the NordICC trial.
Researchers analyzed 358,204 individuals (51% women), aged 55 to 64 years, who were included from 1993 to 2001. The primary outcomes were CRC incidence and mortality.
Results showed colonoscopy prevented an estimated 50 (95% CI, 42-58) cases of CRC and 15 (95% CI, 11-19) CRC-related deaths per 100,000 person-years compared with usual care. This corresponded with a 30% reduced incidence (RR = 0.7; 95% CI, 0.66-0.75) and a 32% reduced mortality (RR = 0.68; 95% CI, 0.61-0.76).
Compared with sigmoidoscopy, the additional benefit of colonoscopy screening was 12 (95% CI, 10-14) fewer CRC cases and four (95% CI, 3-5) fewer deaths per 100,000 person-years, which corresponded with 6.9 (95% CI, 6-7.9) and 7.6 (95% CI, 5.7-9.6) percentage-point reductions, respectively.
Researchers also reported that the number needed to switch from sigmoidoscopy to colonoscopy to prevent one CRC case and one death was 560 (95% CI, 486-661) and 1,611 (95% CI, 1,275-2,188), respectively.
“Colonoscopy screening was estimated to reduce CRC incidence by 30% and CRC mortality by 32%, compared with usual care,” Juul and colleagues concluded. “Compared with sigmoidoscopy screening, colonoscopy screening provided 6.9 percentage points additional reductions in CRC incidence and 7.6 percentage points additional reductions in CRC mortality, which means that the additional preventive effect of colonoscopy compared with sigmoidoscopy was less than what was achieved by introducing sigmoidoscopy screening where no screening existed.”
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