Influence of type 2 diabetes mellitus on mortality in women with breast cancer: A matched case-control study

The study assessed the association between the presence of type2 diabetes mellitus (T2DM) and mortality in women with breast cancer (BC). A matched pair case-control study was conducted at the State Cancer Center, which is located in Xalapa, Veracruz, Mexico. It was matched by age (±3 years) within a cohort of 1442 patients with BC. Descriptive statistics were performed. Analysis through paired odds ratio (OR and multivariate analyses were used to calculate the association between BC mortality and the variables studied. 166 cases and 166 controls with confirmed diagnosis of BC were studied, with a mean age of 52.9 ± 11.9 years. The T2DM was associated with an increased mortality of women with BC (OR = 1.75 95 %CI 1.06–2.89). Similarly, metastasis (OR = 14.17 95 %CI 6.19–32.342), advanced clinical stage (OR = 3.04 95 %CI 1.45 - 6.38), and the molecular subtypes Her2 (OR = 2.0 95 %CI 1.02–3.92), and triple negative (OR = 3.54 95 %CI 1.72–7.32). There was no difference in mean glucose between cases and controls (208.9 ± 132 vs 194.4 ± 90.4 mg/dL, respectively). T2DM was found to be a relevant risk factor for BC mortality in this Mexican population. Thus, it is important to consider the presence and evolution of DM in the prevention programs, diagnostic algorithms and treatments established for BC. •Type 2 diabetes can predispose to more aggressive breast cancer and higher mortality.•Diabetes tend to develop breast tumors that do not express hormone receptors with poor prognosis•Insulin is a potent hormone that activates many pathways leading to an aggressive breast cancer biology