Obesity a significant risk factor for contralateral breast cancer ocurrence.

Abstract

Abstract Abstract #6097 Background: The health consequences of obesity are significant and it's effect on breast cancer outcomes are now being recognized. Several risk factors for contralateral breast cancer recurrence included age, lobular histology, genetic abnormalities and no prior adjuvant systemic therapy. This study's objective was to define the risk of contralateral breast cancer in obese patients following treatment for primary breast cancer.
 Methods: The electronic medical records of pts with histologically proven invasive breast cancer diagnosed between 1981 from 2006 were reviewed. Patients with Stage IV at diagnosis were excluded. Intrammamary breast cancer recurrence was defined as a new diagnosis of invasive or in-situ breast cancer at least 6 months after the diagnosis of primary invasive breast cancer, and it was classified as ipsilateral or contralateral breast cancer. Data on insurance, race, body mass index at diagnosis (BMI) and disease free interval (DFI) was analyzed. National Institutes of Health criteria was used to stratify pts as obese (BMI >30 kg/m2). Differences in DFI were analyzed by BMI.
 Results: Of the 647 pts who were diagnosed with invasive breast cancer, 72 pts (11%) had intrammamary breast cancer recurrence, (28 ipsilateral and 44 contralateral). Pts with contralateral breast cancer in comparison with pts with ipsilateral breast cancer were more likely to be obese at diagnosis (64% vs 25%; p=0.001), to have a higher mean age at diagnosis (51 years vs 46 years; p=0.04) and to have primary breast cancer with ER positive status (67% vs 39%; p=0.05). In univariate analysis, obesity is a significant predictor of contralateral breast cancer. (HR =1.97; p=0.04). In multivariate analysis using Cox regression model, after adjusting for race, menopausal status, stage and SES, age at diagnosis and BMI remain statistically significant predictors for contralateral breast cancer (age at diagnosis: HR=1.09; p=0.006; BMI: HR=4.9; p=0.004).
 Conclusions: In this relatively small patient group, obesity represent a significant risk factor for contralateral breast cancer occurrence. Additional studies are needed to further define the impact of obesity in breast cancer outcomes. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 6097.