title: Aspirin use, body mass index, physical activity, plasma C-peptide, and colon cancer risk in US health professionals.
abstract: Aspirin use decreases colon cancer risk, but this association may vary among population subgroups. The aspirin-colon cancer association was evaluated according to body mass index and physical activity in 1,701 incident colon cancer cases diagnosed during follow-up of 139,310 participants for up to 26 years in 2 US prospective cohort studies that began in 1980 and 1992, respectively. Whether plasma C-peptide levels modified the association was examined by using a nested case-control design (n = 384 cases, 749 controls). Multiplicative and additive interactions were tested. Body mass index did not modify the association; pooled multivariable relative risks for regular aspirin use versus nonuse ranged from 0.74 to 0.75 in the normal weight and obese groups (test for multiplicative interaction, P = 0.75; test for additive interaction, P = 0.66). Pooled multivariable relative risks for regular aspirin use were 0.86 (95% confidence interval (CI): 0.66, 1.11) in the low and 0.67 (95% CI: 0.58, 0.77) in the high physical activity groups with no interaction evident on either the multiplicative or additive scale (P > 0.10). Plasma C-peptide levels also did not modify the aspirin-colon cancer association, with multivariable relative risks of 0.74 (95% CI: 0.50, 1.10) for the low and 0.65 (95% CI: 0.46, 0.92) for the high group. Reductions in colon cancer risk associated with aspirin use were not significantly modified by body mass index, physical activity, or plasma C-peptide level in this study.
authors.affiliation: Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA. xuehong.zhang@channing.harvard.edu
authors.forename: Xuehong
authors.initials: X
authors.lastname: Zhang
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Smith-Warner
authors.forename: Andrew T
authors.initials: AT
authors.lastname: Chan
authors.forename: Kana
authors.initials: K
authors.lastname: Wu
authors.forename: Donna
authors.initials: D
authors.lastname: Spiegelman
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fuchs
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.forename: Edward L
authors.initials: EL
authors.lastname: Giovannucci
mesh_terms: D000328:Adult; D000368:Aged; D001241:Aspirin / Q000008:administration & dosage*; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood*; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D003110:Colonic Neoplasms / Q000097:blood / Q000453:epidemiology*; D005260:Female; D006282:Health Personnel; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009043:Motor Activity; D011446:Prospective Studies; D012306:Risk; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
chemical_list: D002096:C-Peptide; D001241:Aspirin