Relationship between body mass index and preoperative treatment response to aromatase inhibitor exemestane in postmenopausal patients with primary breast cancer

Abstract Background Some studies have shown that high body mass index (BMI) is associated with inferior outcome after adjuvant therapy with anastrozole in breast cancer patients. We aimed to investigate predictive effect of BMI on clinical response to neoadjuvant therapy with exemestane in postmenopausal patients with primary breast cancer. Patients and methods The study group consisted of 109 patients from the JFMC 34-0601 neoadjuvant endocrine therapy trial. Patients were categorized into three groups according to BMI: low (BMI  2 ), intermediate (22 ≤ BMI  2 ) and high (BMI ≥ 25 kg/m 2 ). Statistical analyses were performed to explore the predictive effect of BMI on clinical response. Results Higher BMI correlated with positive progesterone receptor status ( p p  = 0.03). Objective response rates (ORR) were 21.7% in low BMI, 56.0% in intermediate BMI and 60.6% in high BMI, respectively ( p  = 0.01). In a multivariate analysis, low BMI was an independent negative predictor of clinical response. Conclusion Low BMI was associated with a decreased ORR to neoadjuvant endocrine therapy with exemestane. Our results may suggest that the predictive effect of BMI varies according to the type of aromatase inhibitor and objective outcome.