Body mass index and aromatase inhibitors: a step forward in individualizing therapy for breast cancer patients?

Introduction: Progress made in breast cancer management along with treatment-related symptoms has drawn a lot of attention from both scientists and clinicians. Establishing predictive factors for treatment response facilitate tailoring of therapy to each individual patient and leads to a reduction in unnecessary treatments. Body mass index is confirmed to be a risk factor for breast cancer development as well as for disease recurrence, which additionally negatively influence the overall survival. Due to the increased level of fatty tissue in obese and overweight patients, their total level of body aromatase is elevated. This lead to the hypothesis about a worse response to aromatase inhibitors in these groups as compared to normal weight patients, due to incomplete aromatase blockage and thus higher peripheral androgen aromatization. Areas covered: This review aims to summarize the data from clinical trials assessing the effect of BMI on response to AI-based therapy in the setting of breast cancer. Expert commentary: Our conclusion made on the data available to date does not exclude BMI from the list of potential predictive factors however further research in this area is warranted.