[Breast cancer and diabetes mellitus: Complex interactions].

The aim of this literature review was to quantify the incidence and mortality of breast cancer for women treated for a diabetes mellitus and to analyze the complex relationship between these two common diseases.

METHODS: The articles analyzed were extracted from the PubMed database from 2000 to 2015. A total of 22 case/control studies or cohorts were retained, allowing the realization of a meta-analysis.

RESULTS: The incidence of breast cancer for women with diabetes is significantly increased for cohorts (RR=1.32; 95% CI: 1.06 to 1.65) and not significantly for case/control studies (RR=1.46; 95% CI: 0.99 to 2.26). Overall, mortality of women with breast cancer is significantly increased for diabetic patients compared with non-diabetic patients (RR=1.53; 95% CI: 1.23 to 1.90). The links between diabetes and breast cancer are explained by common risk factors (overweight/obesity, qualitative and quantitative dietary errors, physical inactivity), biological changes and the impact of some anti-diabetic treatments or hormonotherapy.

CONCLUSION: Physicians facing a diabetic patient treated for breast cancer have a role in choosing the best anti-diabetic treatment and implementing lifestyle modifications. Diabetic women without breast cancer should participate in organized breast screening programs and have an annual breast clinical examination.