Proximal and Distal Colorectal Cancer Resection Rates in the United States Since Widespread Screening by Colonoscopy

BACKGROUND & AIMS: Screening decreases colorectal cancer (CRC) incidence and mortality. Colonoscopy has become the most common CRC screening test in the United States, but the degree to which it protects against CRC of the proximal colon is unclear. We examined US trends in rates of resection for proximal vs distal CRC, which reflect CRC incidence, in the context of national CRC screening data, before and since Medicare's 2001 decision to pay for screening colonoscopy. METHODS: We used the Nationwide Inpatient Sample, the largest US all-payer inpatient database, to estimate age-adjusted rates of resection for distal and proximal CRC, from 1993 to 2009, in adults. Temporal trends were analyzed using Joinpoint regression analysis. RESULTS: The rate of resection for distal CRC decreased from 38.7 per 100,000 persons (95% confidence interval [CI], 35.4-42.0) to 23.2 per 100,000 persons (95% CI, 20.9-25.5) from 1993 to 2009, with annual decreases of 1.2% (95% CI, 0.1%-2.3%) from 1993 to 1999, followed by larger annual decreases of 3.8% (95% CI, 3.3%-4.3%) from 1999 to 2009 (P < .001). In contrast, the rate of resection for proximal CRC decreased from 30.0 per 100,000 persons (95% CI, 27.4-32.5) to 22.7 per 100,000 persons (95% CI, 20.6-24.7) from 1993 to 2009, but significant annual decreases of 3.1% (95% CI, 2.3%-4.0%) occurred only after 2002 (P < .001). Rates of resection for CRC decreased for adults ages 50 years and older, but increased for younger adults. CONCLUSIONS: These findings support the hypothesis that population-level decreases in rates of resection for distal CRC are associated with screening, in general, and that implementation of screening colonoscopy, specifically, might be an important factor that contributes to population-level decreases in rates of resection for proximal CRC.