The Study: Before keeping your patient on a decade of endocrine therapy, let’s take a broader look at how it can influence one of the major comorbidities in breast cancer survivors. This case-cohort study analyzed the association of endocrine therapy and subsequent development of diabetes among over 2200 Israeli women with early-stage breast cancer. First of all, the overall prevalence of diabetes in the cohort more than quadrupled from 6% in 2002 to 28% in 2015. Among those with no diabetes at baseline, there was a crude incidence rate of new diabetes of 21% at a median follow-up of six years with half of these cases estimated to be attributable to endocrine therapy. Both tamoxifen (HR 2.3) and especially aromatase inhibitors (HR 4.3) were associated with excess diabetes. To no surprise, patients who developed diabetes had higher BMI, less physical activity, and worse diet. These findings are particularly important in light of  diabetes and cardiovascular disease being major competing causes of death in breast cancer survivors and  more women receiving longer duration endocrine therapy. On the bright side, there’s now a type 2 diabetes treatment with a 50% remission rate...but it ain’t popular.
Bottom Line: When weighing the risks and benefits of extended endocrine therapy for early stage breast cancer, add a higher risk of developing diabetes to the risk column. | Hamood, J Clin Oncol 2018