Use of nonsteroidal antiinflammatory drugs and distal large bowel cancer in whites and African Americans.

Despite the belief that the etiology of and risk factors for rectal cancer might differ from those for colon cancer, relatively few studies have examined rectal cancer in relation to use of nonsteroidal antiinflammatory drugs (NSAIDs). The authors evaluated the association between NSAIDs and distal large bowel cancer in African Americans and whites, using data from a population-based case-control study of 1,057 incident cases of adenocarcinoma of the sigmoid colon, rectosigmoid junction, and rectum and 1,019 controls from North Carolina (2001-2006). NSAID use was inversely associated with distal large bowel cancer in whites (odds ratio (OR) = 0.60, 95% confidence interval (CI): 0.46, 0.79). The inverse association was evident for all types of NSAIDs but was slightly stronger with prescription NSAIDs, particularly selective cyclooxygenase 2 inhibitors (OR = 0.38, 95% CI: 0.25, 0.56). Compared with whites, a relatively weak inverse association was found in African Americans (OR = 0.87, 95% CI: 0.55, 1.40), although odds ratio heterogeneity by race could not be confirmed (P = 0.21). In addition, the strength of the association with NSAIDs varied by tumor location, suggesting more potent effects for rectal and rectosigmoid cancers than for sigmoid cancer. The chemopreventive potential of NSAIDs might differ by population and by tumor characteristics.