PrognosticValue of BodyMass Index in LocallyAdvanced Breast Cancer

Purpose:Thepurposeof this retrospective studywas to determine the associationandprognostic valueofbodymassindex(BMI)at thetimeofinitialdiagnosis inpatientswithlocallyadvancedbreast cancer (LABC). The analysis includes the subsets of inflammatory (IBC) and noninflammatory (non-IBCLABC)breastcancer. Experimental Design:We identified 602 patients who had LABC treated on prospective clinical trials. BMI was divided into three groups: (a) V24.9 (normal/underweight), (b) 25.0 to 29.9 (overweight), and (c) z30 (obese). Kaplan-Meier product limit method was used to estimate survival outcomes. Cox proportional hazards were used to determine associations between survival and BMI and to test for an interaction between BMI and breast cancer type. Results: Eighty-twopercenthadnon-IBCLABCand18%hadIBC.Obesepatients tendedtohavea higher incidence of IBC compared with overweight and normal/underweight groups (P = 0.01). Median follow up was 6 years for all patients. Median overall survival (OS) and recurrence-free survival (RFS) were 8.8 and 5.9 years, respectively. Patients with LABCwhowere obese or overweight had a significantly worse OS and RFS (P = 0.001) and a higher incidence of visceral recurrence compared with normal/underweight patients. In a multivariable model, BMI remained significantly associatedwith both OS and RFS for the entire cohort.The interactions between BMI andLABC subsets andbetweenBMIandmenopausal statuswerenot statistically significant. Conclusion:PatientswithLABCandhighBMIhaveaworseprognosis.Evaluationof thebiological factors associatedwith thisobservationcanprovide tools foradditional therapeutic interventions. Locally advanced breast cancer (LABC) is an important public health problem, representing f5% of newly diagnosed breast cancers among women enrolled in periodic screening programs and up to 50%of women inmedically underserved regions of the United States andmany developing countries (1). Inflammatory breast cancer (IBC), an aggressive and highly lethal form of breast cancer, represents a distinct subset of LABC that constitutesf1% to 6% of breast cancers diagnosed in the United States (2). A number of factors including tumor size, number of involved lymph nodes, estrogen receptor status, nuclear grade, and human epidermal growth factor receptor-2 status are known to influence prognosis of breast cancer (3, 4). A growing body of evidence suggests that body weight is also strongly associated with increasing risk of developing breast cancer (5, 6). Furthermore, patients with higher body mass index (BMI) have been found to have worse outcome (7, 8) and a higher risk of recurrence regardless of age or menopausal status (9, 10). In addition, women with higher fat content tend to have larger tumors and more involved lymph nodes at presentation (11, 12). Earlier studies have shown that high BMI was associated not only with a higher risk of developing IBC (13) but also with shorter survival (14). At the University of Texas M. D. Anderson Cancer Center, we have treated patients with locally advanced breast cancer in clinical trials using similar multimodality therapies (15, 16). The uniformity of treatments and follow-up procedures gives us the opportunity to evaluate the effect of biological factors with minimal confounding bias of other variables. We therefore decided to perform a retrospective study to determine the association and prognostic value of BMI in LABC and to determine if the effect of BMI was different between the non-IBC LABC and IBC subgroups.