The Impact Of Newly Diagnosed Diabetes Mellitus On Colorectal Cancer Risk In Patients Without Colorectal Polyps

Objective:To evaluate the relationship between newly diagnosed DM and CRC risk and distinguish the high-risk period of CRC in the duration of DM.Furthermore,we evaluated whether the relationship between DM and CRC risk would be influenced by the baseline characteristics.Methods:A total of 11632 patients without colorectal polyps and DM history were identified in the Korean Multicenter Cancer Cohort(1993-2003).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.To evaluate DM impact on CRC risk in relation to baseline characteristics,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.Results:Overall,6.9%(n=802)of patients were newly diagnosed DM.At a median follow-up of 11.3 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 increased CRC risk with DM in all subsets(≥3yr: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 multivariable Cox regression,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 impact of DM on cancer-free survival was slight as predicted CRC risk less than 5%.Conclusion:Newly diagnosed DM was associated with a higher risk for CRC.This impact was moderately affected by baseline characteristics.