Abstract 2900: Risk of recurrence of colorectal neoplasia among type 2 diabetes mellitus patients randomized to placebo in the Polyp Prevention Clinical Trials

Abstract

Abstract Introduction: Diabetes Mellitus (DM) has been reported to be associated with an increased risk of colorectal cancer is several case-control studies. However, very limited data have examined the risk of recurrence of colorectal neoplasia (CRN) among individuals with type 2 DM. This study examined the risk of recurrence of CRN (either adenomas or carcinoma) among individuals with type 2 DM compared to those without type 2 DM. Methods: Retrospective cohort study evaluated subjects recruited into several randomized clinical trials (RCTs) (Antioxidant Polyp Prevention Study, the Calcium Polyp Prevention study, and the Aspirin/Folate Prevention Study). Diagnosis of type 2 DM was established by previous medical diagnosis and/or anti-diabetic medication use. Participants had to have undergone colonoscopy to the cecum, with removal of all polyps, within three to four months before study entry. Also, they must have had colonoscopies during follow-up study periods (as outlined for each protocol). Logistic regression was employed to estimate the association between type 2 DM and CRN using STATA 10.0. Results: 2,915 individuals (2068 women; 85.3% White; mean age 59.7 ± 9.3 years) were enrolled into any of the three RCTs. 882 (30.3%) subjects were assigned to placebo vs. 2033 (69.7%) to active drug; mean follow-up time was 35.0 ± 3.9 months from randomization to first colonoscopy. A total of 208 subjects had type 2 DM (mean age 62.9 ± 7.6 yrs, 75.5% females), of which 61(29.3%) were assigned to the placebo arm. Colorectal adenomas developed in 44.5% (27/61) and 55.1% (410/744) of DM and non-DM individuals, respectively (p=0.40) assigned to the placebo arm. While advanced colorectal adenomas (≥ 1 cm in size or advanced histology) developed in 9.8% (9/61) and 9.3% (69/744) of DM and non-DM individuals, respectively (p=0.89). Colorectal cancer developed in 1.64% (1/61) of DM patients vs. 0.4% (3/744) of non-DM patients (p=0.19). There was no statistically significant association between location of CRN, number/size of adenomas, or tumor stage and DM. Discussion: Recurrence of colorectal adenomas was not increased among patients with DM compared to non-DM patients. Similarly, occurrence of colorectal advanced lesions was not increased in DM patients compared to non-DM patients. A small number of subjects with DM and short follow-up time may have limited the power of the study to detect differences in CRN. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2900.