86P - The impact of newly diagnosed diabetes mellitus on cancer-free survival in patients without colorectal polyps: A secondary analysis of Korean multicenter cancer cohort

Abstract

BackgroundObservational studies show that diabetes mellitus (DM) is associated with a higher risk of colorectal cancer (CRC). However, whether the relationship between DM and CRC will be influenced by the baseline characteristics of patients is still unclear. MethodsA total of 11632 patients without colorectal polyps and DM history were identified in the Korean Multicenter Cancer Cohort (1993-2005) and categorized in the diabetic group (DM; fasting glucose≥126mg/dL) versus normal group (non-DM; all other patients). Cancer-free survival was analyzed using the Kaplan-Meier method, log-rank test, Cox proportional hazards models. The two groups (DM vs non-DM) were matched using propensity scores(PS) to control selection bias. To evaluate DM impact on CRC risk in relation to baseline characteristics, first multivariable Cox regression analysis was used to predict CRC risk in patients without DM, then interaction between predicted CRC risk and DM status was performed. ResultsOverall, 6.9% (n = 802) of patients were newly diagnosed diabetes mellitus. At a median follow-up of 12.0 years, patients with DM were associated with lower cancer-free survival(unadjusted HR, 1.83; 95%CI: 1.11 to 3.01). Landmark analyses limited to long-term survivors demonstrated improved cancer-free survival with DM in all subsets (≥3yr: unadjusted HR,1.93(95%CI:1.13 to 3.29); ≥5yr: HR, 2.04(CI:1.15 to 3.63); ≥10yr: HR, 2.50(CI: 1.19 to 5.25)). In the PS-matching cohorts, however, 10-yr cancer-free survival was not markedly higher in the non-DM group versus the DM group (99.0% vs 98.8%; p = 0.57). In multivariable Cox regression, the non-DM group, age, sex, BMI, alcohol consumption history and cigarette smoking history were predictors of CRC risk. This model was used to predict the 10-yr CRC risk. The interaction between predicted CRC risk and DM status was not significant. Specifically, the impact of DM on cancer-free survival was slight as predicted CRC risk less than 5%. ConclusionsIn this large prospective study, newly diagnosed diabetes mellitus was associated with a higher risk for colorectal cancer. This impact largely affected by baseline characteristics. Legal entity responsible for the studyXiong Chen. FundingHas not received any funding. DisclosureThe author has declared no conflicts of interest.