Abstract 594: Associations of hemoglobin A1c with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC)

Abstract

Self-reported type 2 diabetes mellitus (T2DM) is convincingly associated with higher risks of liver, pancreatic, colon, rectal, female breast, and endometrial cancers, and may also be associated with higher risks of ovarian, bladder and kidney cancers. This evidence largely relies on self-reported T2DM, which does not properly classify the many individuals with pre-diabetes or with undiagnosed T2DM or adequately reflect glucose control among people with T2DM. To clarify these associations, we conducted a case-cohort analysis of hemoglobin A1c (HbA1c), an indicator of circulating glucose over the past 2-to-3 months used to diagnose and monitor T2DM. Participants were identified from the CPS-II NC. From an initial cohort of 32,328 participants who were cancer-free and provided a blood sample at baseline in 1998-2001, we selected a random sub-cohort of 3,000 participants. Further, we selected all participants diagnosed between baseline and June, 2013 with a verified, incident cancer of the colorectum (n=479), liver (n=35), pancreas (n=176), female breast (n=889), endometrium (n=155), ovary (n=93), bladder (n=344), or kidney (n=110). Weighted Cox proportional hazards regression models estimated hazards ratios (HRs) and 95% confidence intervals (CI) for associations of HbA1c with cancer risks combined and stratified by organ site. HRs were adjusted for age, gender, smoking, physical activity, alcohol, and hormone-use (women only). HbA1c levels reflective of clinically-defined T2DM (>=6.5%), compared to HbA1c levels in the non-diabetes range ( =6.5%) were at higher risk of CRC whether they self-reported T2DM (HR: 1.54), or not (HR:1.56), whereas participants who self-reported T2DM but had good glycemic control (HbA1c = Citation Format: Peter T. Campbell, Christina Newton, Eric J. Jacobs, Michael Pollak, Susan M. Gapstur. Associations of hemoglobin A1c with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort (CPS-II NC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 594.