The Impact of Obesity on Breast Cancer: A Retrospective Review

Obesity has been linked to many adverse health consequences, including breast cancer; however, the impact on clinical presentation, tumor characteristics, and survival outcomes has yet to be clearly defined. Retrospective review of a prospectively collected database of patients treated at a single institution for invasive breast cancer from 2000-2008 comparing two groups: nonobese (body mass index of < 30) and obese (body mass index of a parts per thousand yen30) patients. Continuous variables, categorical variables, and survival data were analyzed. Of 1352 total patients, 76% were classified as nonobese and 24% were obese. When comparing age, obese patients presented less frequently than nonobese patients < 50 years old (10% vs. 90%), and when comparing patients > 50 years old (18% vs. 82%, P = 0.0019). Obese patients were more likely to present with disease detected by imaging when compared to nonobese patients (67% vs. 56%, P = 0.0006). Obese patients had larger tumors (1.7 cm vs. 1.4 cm, P < 0.001) and higher rates of lymph node (LN) metastases (31% vs. 25%, P = 0.026). On multivariate analysis, obesity was associated with nonpalpable tumors, larger tumors, a higher incidence of LN metastasis, lower incidence of Her2 positivity, lower incidence of multifocality, and less likely to undergo reconstruction after mastectomy. Obese patients clinically present at older ages with mammographically detected breast cancer at more advanced stages than nonobese patients. Strategies to encourage screening among the obese patient population are important.