Abstract 5313: Associations of calcium and dairy product intakes with colorectal cancer risk among older women: the Iowa Women's Health Study

Abstract

Abstract Calcium has been consistently modestly associated with lower risk of colorectal cancer, which remains the second leading cause of cancer deaths among men and women combined in the United States. Dairy products, a major source of dietary calcium, have also been consistently inversely associated with colorectal cancer, although inconsistencies in relation to high-fat dairy products have been noted. Limited evidence suggests that dairy products may contain components other than calcium and fat, such as insulin-like growth factor 1 (IGF-1), that may be independently directly associated with risk of colorectal and other cancers. Data from the Iowa Women’s Health Study, a prospective cohort study, were used to investigate associations of calcium, dairy products, and the non-calcium component of dairy products with colorectal cancer incidence. Dietary data were collected using a semiquantitative food frequency questionnaire (FFQ) mailed to 55 – 69 year-old women in 1986 who had a valid Iowa driver’s license. Among participants with no history of cancer at baseline and who satisfactorily completed their FFQ (n=35,221), through follow up in 2012, 1,731 incident cases of colorectal cancer were documented via the Iowa SEER registry. To investigate total dairy and total, whole, and non-fat milks independent of their calcium components, we used the residuals from linear regression models of their associations with dietary calcium. Associations of the calcium and dairy product variables with colorectal cancer incidence were estimated using multivariable Cox proportional hazards regression. For those in the highest relative to those in the lowest quintiles of intakes, the adjusted hazards ratios and 95% confidence intervals (CI) were 0.81 (CI 0.67-0.98; P-trend 0.004) for total calcium, 0.85 (CI 0.68-1.03; P-trend 0.07) for dietary calcium, and 0.85 (CI 0.68-1.06; P-trend 0.16) for supplemental calcium. For total dairy and total milk, the corresponding findings were 0.79 (CI 0.66-0.94; P-trend 0.01) and 0.82 (CI 0.69-0.96; P-trend 0.09), respectively. Low-fat dairy products, non-fat milk, and residuals of total dairy products and total and non-fat milk were not associated with colorectal cancer. These results are consistent with previous findings of lower colorectal cancer risk with higher intakes of calcium and dairy products, but provide little support for the hypothesis that the non-calcium, non-fat component of dairy products may be associated with colorectal cancer. Citation Format: Caroline Um, Anna Prizment, DeAnn Lazovich, Roberd M. Bostick. Associations of calcium and dairy product intakes with colorectal cancer risk among older women: the Iowa Women's Health Study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5313. doi:10.1158/1538-7445.AM2017-5313