P1-06-21: Relationship between Body Mass Index and Preoperative Treatment Response to Aromatase Inhibitor Exemestane in Postmenopausal Patients with Primary Breast Cancer.

Abstract

Abstract Background: Some studies have shown that high body mass index (BMI) is associated with inferior outcome after adjuvant therapy with non-steroidal aromatase inhibitor, anastrozole in breast cancer patients. We aimed to investigate predictive effect of BMI on clinical response to neoadjuvant therapy with steroidal aromatase inhibitor, 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 in which postmenopausal patients with estrogen receptor (ER)-positive primary breast cancer were administered exemestane (25 mg/day) for 24 weeks before surgery. Patients were categorized into three groups according to BMI: low (BMI < 22 kg/m2), intermediate (22 ≤ BMI < 25 kg/m2) and high (BMI ≥ 25 kg/m2). Statistical analyses were performed to explore the predictive effect of BMI on clinical response using a multivariable logistic regression model. Results: Higher BMI correlated with positive progesterone receptor status (p < 0.01) and low Ki-67 index (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, only 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. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-06-21.