Gastrointestinal Cancer Incidence in Type 2 Diabetes Mellitus; Results from a Large Retrospective Population-Based Cohort Study in the UK

Abstract

Background: Type 2 diabetes mellitus (T2DM) has been suggested as a risk factor for liver, pancreatic, and colorectal cancer. T2DM patients show higher incidences of these cancers compared to the non-diabetic (non-DM) population. Current evidence, however, is inconsistent with respect to the incidences of other gastrointestinal (GI) malignancies. Objectives: To determine incidence rates (IRs) of all GI cancers in patients with and without T2DM. Methods: A retrospective cohort study was conducted using the UK Clinical Practice Research Datalink (CPRD) during 1988-2012. A T2DM cohort of antidiabetic drug users was matched to a non-DM reference cohort, by age, sex, and practice. Crude incidence rates (IRs) per 100,000 person-years (105 py) and 95% confidence intervals (CI) were calculated, stratified by age, sex, and calendar period. IRs were compared using the normal theory test. Results: 333,438 T2DM subjects and 333,438 nonDM subjects were analyzed, with a total duration of follow-up of >3.6 million py and 10,977 observed GI cancer cases. Overall, IRs of any GI cancer (IR 330 vs. 276 per 105 py), liver cancer (IR 26 vs. 8.9 per 105 py), pancreatic cancer (IR 65 vs. 31 per 105 py), and colon cancer (IR 119 vs. 109 per 105 py) were significantly higher in the T2DM cohort compared to the non-DM cohort, whereas the IR of esophageal cancer was significantly lower (IR 41 vs. 47 per 105 py, p<0.05). After stratification by sex, the higher IR of colon cancer only remained statistically significant in men, and the lower IR of esophageal cancer only remained statistically significant in women. No differences in IRs between the T2DM and non-DM cohort were found for gastric, biliary, and rectal cancer. Conclusions: Higher IRs for liver, pancreatic, and colon cancer were found in T2DM patients versus nonDM controls. Furthermore, we found no differences in IRs for gastric, biliary, and rectal cancer. The results of this study underline the importance of clinical awareness for liver, pancreatic and colon cancer in the T2DM population. In addition, the lower observed IRs of esophageal cancer in T2DM patients warrants further investigation.