[3051] Triple negative invasive breast cancer: association with low body mass index and race. Westrup JL, Lash TL, Chi DD, Stead LA, Sobieraj JE, Blanchard RA, King TC, Rosenberg CL. Boston University Medical Center, Boston, MA; Boston University School of Public Health, Boston, MA Background: The triple negative immunophenotype (ER-/PR-/HER2-) constitutes 15% of all invasive breast cancers and is associated with a poor prognosis. This phenotype accounts for the vast majority of basal subtype breast cancers identified by expression profiling. We sought to define the clinical and pathologic features of the patients and their triple negative invasive breast tumors in a diverse population. Material and Methods: We established a database from an ethnically and socio-economically diverse patient population receiving care at a tertiary facility that is the largest safety net hospital in New England, with IRB approval. We identified female invasive breast cancer patients diagnosed from 1998 - 2006 for whom there was information at diagnosis on tumor grade, stage, ER/PR expression, HER2 status, patient age, BMI using NHLBI cut offs, and self identified racial group. All tumors were assessed using IHC and image analysis. HER2 2+ tumors were further assessed by FISH. We used contingency tables and multivariate logistic regression to determine associations between patient and tumor characteristics. Results: 310 cases with complete information were identified; they were racially diverse (31% white, 36% black/African American, 9% Hispanic/Latino, and 24% other). Elevated BMI was common (24% underweight/normal, 27% overweight, 40% obese, and 8% extremely obese). 68%were post-menopausal, 62% were ER+/PR+, 11% were HER2 over expressed/amplified, and 19% were triple negatives. The probability of triple negative tumors was associated with race/ethnicity (p<.01) and with lower BMI (p=0.03). Mutually adjusting for race and BMI, the odds of triple negative tumors were 3.3 fold higher (95% CI 1.5, 7.0) in black/African American women than in white women, and 0.43 fold lower (95% CI 0.20, 0.92) in obese women than in normal/underweight women. After adjusting for race/ethnicity, there was a significant decreasing trend in the proportion of triple negative tumors with increasing category of BMI (p=0.02). The proportion of patients with triple negative tumors did not vary significantly with age. Our database also identified previously described correlations between: increasing patient age and hormone receptor status (p=0.03), race and hormone receptor status (p=0.01), elevated post-menopausal BMI and ER expression status (p=0.09) and triple negative tumors and increased grade (p<.01). Discussion: We report significant independent associations between triple negative invasive breast cancer and both race and lower BMI. Our findings suggest that triple negative tumors are more prevalent in particular racial/ethnic groups, who may have distinct genetic backgrounds; and they may be less dependent on estrogen exposure, presumably from peripheral conversion, for growth stimulation. San Antonio Breast Cancer Symposium Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.