In contrast, for distal cancers the protective benefit of colonoscopy extended beyond 7 years: Screening colonoscopy provided a significant 42% cancer-rate reduction, compared with no screening, more than 7 years out.
The analysis also showed that the statistically significant protective benefit from polypectomy lasted for just 3 years for all cancer locations, with a 52% protection rate compared with no screening. For distal cancers a significant protective effect lasted for 5 years, but for proximal cancers polypectomy did not provide significant protection, even during the first 3 years after the procedure.
An additional multivariate analysis showed cumulative protection from multiple colonoscopies. A single screening colonoscopy cut the rate of incident cancers, both proximal and distal, by a statistically significant 47%, but two colonoscopies cut the risk by 59% and three or more colonoscopies cut the risk by 64%.
Dr. Lochhead said that he had no disclosures.