The impact of waist-to-hip ratio (WHR) on survival in metastatic breast cancer patients treated with aromatase inhibitors (AIs)

Abstract

1070 Background: Aromatase inhibitors represent a novel hormonal therapy for breast cancer. Aromatase is expressed in the ovaries, brain, bone and, adipose and breast tissue. Elevated WHR, representing a higher abdominal fat distribution, has been associated with both the development of and mortality from breast cancer. Therefore, we aimed to identify whether abdominal fat distribution could affect the outcome in metastatic breast cancer patients treated with AIs. Methods: A total of 46 metastatic breast cancer patients treated with first line hormonal therapy were enrolled in this study. Pretreatment body weight, height, BMI and WHR were measured. Estrogen, progesteron and c- erb-B2 receptor status were also evaluated in analyses. Univariate and multivariate Cox regression analyses, and Kaplan Meier survival curves subjected to log rank testing were utilized for the survival analyses. Forward likelihood ratio was used for the multivariate selection process. A P value < 0.05 was considered to be significant. Results: Median age was 51 years (range 28 - 75). 36 patients were treated with letrozole and 10 patients with anastrozole. Median body weight, height, WHR and BMI were found to be 68.5 kg (range 46 - 115), 156 cm (range 137 - 167), 0.91 (range 0.7 - 1.2), and 28.7 (range 18 - 45), respectively. Factors associated with overall survival in the univariate analysis were age, c-erb-B2 expression intensity (+++ versus others by immunohistochemistry), and WHR, whereas only WHR retained significance in the multivariate analysis. Likewise, predictors of progression free survival were c-erb-B2 expression intensity and WHR. However, none of these factors was significant in the multivariate analysis. Median overall survival figures were 472 days versus unreached for patients with a WHR of <0.92 and =0.92 (Log rank statistic = 9.76, P = 0.002). Similarly, the corresponding progression free survival figures for patients with a WHR of <0.92 and =0.92 were 423 versus 1,004 days (Log rank statistic = 6.37, P = 0.012). Conclusions: This is the first report examining and suggesting the value of abdominal fat distribution in relation with benefit from AIs in metastatic breast cancer. Our results should be validated in larger series. No significant financial relationships to disclose.