[Breast cancer, the risk attributable to type 2 diabetes]

Several studies have evaluated the association between a history of type 2 diabetes (T2D) and risk of breast cancer (BC), with controversial results. However, information regarding the population-attributable risk percent (PAR%) remains scarce. Objective: To estimate the association and the PAR% for BC and T2D, lifestyle and gynecologic factors in women in Mexico City.

This case-control study was performed from May-December 2020. Women >40 years of age, from Mexico City, with a confirmed diagnosis for BC were included as cases. Controls were women with a BIRADS 1 or 2 mammography or an ultrasound clear of any BC suggestive findings.

A total of 134 cases and 134 controls were included. A higher risk for BC was identified among women who did not perform routine physical activity and those who had a history of hormonal contraceptive use > 5 years. The use of hormone replacement therapy (HRT) was associated with an odds ratio (OR) of 5.0 (p = 0.22) in the first model. After adjustment, HRT was associated with an OR of 2.92 (p=0.492) in the second and an OR of 3.6 (p = 0.753) in the third model. T2D was associated with an OR of 1.04 (p = 0.96) in the first model; an OR of 0.65 (p = 0.65) in the second model and an OR of RMa 0.75(p = 0.79) for the third model.

In this case-control study, there was no significant association identified between a T2D diagnosis and BC.