Survival Analysis of Diabetic Colorectal Cancer Patients On Metformin in Brunei Darussalam

Abstract

Metformin, an antihyperglycemic drug, has been associated with antineoplastic effects and could potentially improve colorectal cancer prognosis. There are several conflicting data with regards to the association between metformin use and CRC survival. This study aims to provide more information on the subject while addressing certain limitations. The study was a retrospective cohort study that included colorectal cancer patients from the only cancer centre in the country, The Brunei Cancer Center (TBCC), treated between July 2014 and July 2019. Kaplan-Meier and multivariate Cox proportional hazard regression models were used to analyze the data, construct survival curves and adjust for comorbidities. Of a total of 112 diabetic patients, 79 patients (70.5%) were on metformin and 33 patients (29.5%) were on other anti-hyperglycemic medications. An association between metformin use and lower incidence of stage IV colorectal cancer (p = 0.046) was observed, but no significant difference between the metformin group and the non-metformin group in terms of survival probability (log rank p = 0.13) was shown. Analysis using multivariate models showed that metformin reduces the hazard ratio by 31.2%, although, this value is statistically insignificant (HR, 0.688; 95% CI 0.286 – 1.654; p = 0.403). Among the diabetic colorectal cancer patients, there was no association between survival and metformin therapy. This data reflects the correlation of metformin use and CRC survival within the nation for all CRC diabetic patients diagnosed between July 2014 and July 2019. However, for further extrapolation of data, the association between cancer progression and metformin use requires further investigation and high-powered clinical trials are needed to support these findings.