Abstract PD09-02: Prognostic Effect of Obesity on Breast Cancer

Background: Body mass index (BMI), prior estrogen use, and family history have been described as risk factors for invasive breast cancer. Our purpose was to investigate the influence of obesity on established prognostic pathologic and molecular characteristics of breast cancer. Material and methods: Five-hundred and twelve female consecutive breast cancer patients of mean age 53±11 years were included in this study. Data were recorded in a prospective electronic databank upon first presentation. Risk factors (BMI, family history, prior estrogen use, menopausal status, parity, metabolic syndrome, smoking, alcohol, hypertension, hyperlipidaemia and diabetes) as well as histologic characteristics (TNM, nodal status, grade, LVI) and tumor phenotype (ER, PR, Cerb-B2) were obtained. Patients with a BMI<27 were considered of normal weight whereas patients with a BMI≥27 were considered as obese. Univariate and logistic regression analysis were performed. Results: The 2 groups did not differ for age (p=ns). Patients with a BMI≥27 were more frequently node positive, had a higher incidence of grade 3, LVI positive tumors and had more often a positive family history of breast cancer (P<0.05). On the contrary, patients with a BMI<27 reported more frequently prior estrogen use and were more commonly nulliparous (P<0.05). Regression analysis confirmed that in patients with BMI<27 age and menopausal status were associated with node positive disease, independently of tumor phenotype, grade, LVI, family history, estrogen use and parity (0.951, 95%CI 0.91-0.99 and 3.232, 95%CI 1.2-8.5). Using the same analysis, in patients with BMI≥27 LVI was associated with node positive disease, independently of all other factors (5.253, 95%CI 1.1-26.9).

Discussion: Different risk factors appear to influence lean and obese breast cancer patients. Patients with BMI<27 more frequently have a history of estrogen use and nulliparity. Age and menopausal status are independently associated with node + disease in lean patients. Obese patients (BMI>27) have more frequently positive family history and more aggressive histology (node +, grade 3, LVI+). LVI in obese patients appears to be independently associated with node + disease.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr PD09-02.