Background: Results from case-control studies outside the United States have been conflicted about the efficacy of colonoscopy for reducing cancer risk in the right colon. To contribute to this discourse from an alternative perspective, we analyzed high-quality surveillance data to report on recent trends in population-based colorectal cancer incidence rates by tumor location in the United States.
Methods: Data from cancer registries in the Surveillance, Epidemiology, and End Results Program were analyzed to examine colorectal cancer incidence trends from 1992 through 2008 among individuals aged ≥ 50 years (n = 267,072). Joinpoint regression analysis was used to quantify annual percent change in age-standardized rates by tumor location and disease stage.
Results: Incidence rates for right-sided colon tumors decreased annually by 2.6% (95% CI: 2.0-3.2) since 1999 in men and 2.3% (CI: 1.6-3.0) since 2000 in women, after remaining stable during the previous seven/eight years. Incidence rates for left-sided tumors were generally decreasing from 1992 to 2008 in both sexes. Beginning in 1999/2000, substantial, almost identical annual declines occurred for late-stage disease in both the right and left colon: 3.9% (CI: 3.1-4.8) and 4.2% (CI: 3.5-4.9), respectively, in men; and 3.3% (CI: 2.5-4.1) and 3.3% (CI: 2.8-3.8) in women.
Conclusion: Large declines in the incidence of right-sided colon tumors among individuals 50 years and older began around 2000.
Impact: Increased colonoscopy utilization during the past decade may have contributed to a reduction in risk for cancers in both the right and left colorectum in the United States.
©2012 AACR.