Survival of Colorectal Cancer Patients With Diabetes Mellitus: A Meta-Analysis

OBJECTIVES: Diabetes mellitus (DM) is associated with an elevated risk of various cancers, including colorectal cancer (CRC). Similarly, pre-existing DM may also influence prognosis among patients with CRC. We performed a systematic review and meta-analysis to assess the association between DM and risk of death and relapse after a diagnosis of CRC.

METHODS: PubMed, Scopus, Web of Science, The Cochrane Library and Embase were searched from inception until July 2019 for studies reporting prognosis of patients with DM and CRC. The primary outcome of the study refers to overall mortality in patients with vs without diabetes. Secondary endpoints were cancer-specific mortality and progression or relapse-free survival. The risk of death and relapse are reported as hazard ratio (HR) with 95% confidence interval (CI), and an HR >1 was associated with worst outcome in patients with diabetes compared to those without diabetes.

RESULTS: Mortality and relapse associated with DM in patients with CRC were evaluated among 5,267,980 participants (total of 82 studies). Overall, concomitant diagnosis of CRC and DM were associated with an independent increased risk of overall mortality (HR, 1.21; 95% CI, 1.17 to 1.25; p<0.01) and CSM (HR, 1.11; 95% CI, 1.05 to 1.17; p<0.01). Patients were also at increased risk of relapse (HR, 1.09; 95% CI, 1.02 to 1.16; p<0.01).

CONCLUSIONS: In CRC patients with DM, diabetes decreased survival and increased the risk of relapse. Adequate control of lifestyle choices, more intensive follow ups, use of some oral antidiabetics, dietary restrictions, physical activity and monitoring of diabetes-associated complications are measures for reducing mortality in this setting.