Colonoscopy Works!

Recent case-control and colonoscopy studies have consistently identified reductions in colorectal cancer (CRC) incidence and mortality following colonoscopy. Randomized, controlled trials have established a reduction in distal CRC incidence and mortality following sigmoidoscopy. To further examine this issue, researchers analyzed long-term, follow-up data from the Nurses' Health Study and the Health Professionals Follow-up Study.

Results of 22 years of follow-up of 88,902 participants (1,738,396 person-years) are below:

• CRC incidence: 1815

• CRC deaths: 474

• Reductions in incidence associated with polypectomy (43%), negative sigmoidoscopy (40%), and negative colonoscopy (56%)

• A 27% reduction in proximal cancer incidence associated with negative colonoscopy (but not with sigmoidoscopy)

• Reductions in CRC mortality after screening sigmoidoscopy (41%) and after screening colonoscopy (68%)

• A 53% reduction in proximal CRC mortality after screening colonoscopy (but not after sigmoidoscopy)

• Lasting reductions in CRC incidence after negative colonoscopy (≤3 years, 65%; 3.1 to 5 years, 60%; 5.1 to 10 years, 48%; 10.1 to 15 years, 74%)

• Lasting reduction in CRC incidence from 5.1 to 15 years after negative colonoscopy for both proximal (40%) and distal CRC (65%)

• Attenuated reduction in cancer incidence after polypectomy in patients with high-risk adenomas

• Higher likelihood of CpG island methylator phenotype (odds ratio, 2.19) or microsatellite instability (OR, 2.10) in cancers occurring ≤5 years after colonoscopy