title: Dietary carbohydrate, glycemic index, and glycemic load in relation to colorectal cancer risk in the Women's Health Initiative.
abstract: Evidence implicating hyperinsulinemia and insulin resistance in the etiology of colorectal cancer suggests that a diet characterized by a high glycemic index and load may increase the risk of this disease, but previous studies have yielded inconsistent results. We assessed the association between intake of total carbohydrates, sugars, fiber, and the glycemic index (GI) and glycemic load (GL) of individual diets, and risk of developing colorectal cancer among 158,800 participants in the Women's Health Initiative (WHI). We used a GI/GL database developed specifically for the WHI food-frequency questionnaire. Over an average of 7.8 years of follow-up, 1,476 incident cases of colorectal cancer were identified. Cox proportional hazards models were used to estimate the association between dietary factors classified by quintiles and risk of colorectal cancer, with adjustment for covariates. Total carbohydrate intake, glycemic index, glycemic load, and intake of sugars and fiber showed no association with colorectal cancer. Analyses by cancer subsite also yielded null results, with the exception of a borderline positive association between glycemic load and rectal cancer (HR for the highest versus lowest quintile 1.84, 95% confidence interval 0.95-3.56, p for trend 0.05). Analyses stratified by tertiles of body mass index and physical activity showed no evidence of effect modification by these factors. Results of this large study do not support of a role of a diet characterized by high glycemic index or load in colorectal carcinogenesis in postmenopausal women.
authors.affiliation: Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA. gkabat@aecom.yu.edu
authors.forename: Geoffrey C
authors.initials: GC
authors.lastname: Kabat
authors.forename: James M
authors.initials: JM
authors.lastname: Shikany
authors.forename: Shirley A A
authors.initials: SA
authors.lastname: Beresford
authors.forename: Bette
authors.initials: B
authors.lastname: Caan
authors.forename: Marian L
authors.initials: ML
authors.lastname: Neuhouser
authors.forename: Lesley F
authors.initials: LF
authors.lastname: Tinker
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Rohan
mesh_terms: D000368:Aged; D001786:Blood Glucose / Q000378:metabolism*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000097:blood / Q000453:epidemiology* / Q000209:etiology*; D016001:Confidence Intervals; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D005260:Female; D005500:Follow-Up Studies; D038321:Glycemic Index; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D017698:Postmenopause; D016016:Proportional Hazards Models; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013997:Time Factors; D014481:United States / Q000453:epidemiology
chemical_list: D001786:Blood Glucose; D004040:Dietary Carbohydrates