Abstract P6-08-09: Self-identified race and Area Deprivation Index in patients with invasive lobular carcinoma of the breast: associations with tumor characteristics and event free survival
Authors: Kaur Mandeep , Patterson Anne , Molina-Vega Julissa , Rothschild Harriet T. , Clelland Elle , Abel Mary Kathryn , Esserman Laura J. , Olopade Olufunmilayo I. , Mukhtar Rita 
Published: March 2023

Abstract
Objectives: Investigators have shown a relationship between race/ethnicity and survival in invasive lobular carcinoma (ILC), the second most common type of breast cancer. While non-white patients with ILC were shown to have worse outcomes, there are no data evaluating the impact of socioeconomic factors. Herein we evaluated the relationship between self-reported race and socioeconomic factors with tumor features and outcomes in early-stage patients with ILC. Methods: We used chi-squared tests, t-tests, the Kruskal-Wallis test, multivariate Cox proportional hazards models, and tests for trend in Stata 16.1 to evaluate race, area deprivation index (ADI), and event-free survival (EFS) in a single institution cohort of patients with stage I-III ILC. Race was self-reported and categorized as black, white, or other. ADI was ascertained from a publicly available database using measures of income, education level, employment, and housing quality to provide information about neighborhood adversity. ADI was evaluated in quintiles, with quintile 1 signifying the least resource deprived neighborhoods, and quintile 5 signifying the most resource deprived. Tumor receptor subtype was defined by estrogen receptor (ER), progesterone receptor (PR), and HER2 status. Body mass index (BMI) of 18.5-24.9 kg/m2 was categorized as normal, 25-29.9 kg/m2 as overweight, and ≥ 30 kg/m2 as obese. Results: Of 823 patients in our institutional database, self-reported race/ethnicity data were available for 808, with 28 (3.5%) identifying as black, 638 (79.0%) as white, and 142 (17.6%) as other. ADI data were available for 816 patients, with 174 (21.3%) in quintile 1, 210 (25.7%) in quintile 2, 110 (13.5%) in quintile 3, 163 (20.0%) in quintile 4, and 159 (19.5%) in quintile 5. Tumor receptor subtype differed by ADI, with patients in the highest ADI category (most resource-deprived) being most likely to have ER positive, PR positive, and HER2 negative tumors (81.8% in ADI category 5 versus 69.0% in ADI category 1, p=0.001). Those in higher ADI categories were also more likely to have lymphovascular invasion (9.2% in ADI category 5 versus 4.3% in ADI category 1, p=0.008), and were less likely to present with stage I disease (55.5% in ADI category 5 versus 67.9% in ADI category 1, p=0.002). BMI was not associated with tumor characteristics, but was significantly associated with ADI, with a significant trend towards higher BMI in areas of higher ADI (p&lt; 0.001). Among patients who self-identified as black, age at diagnosis was significantly higher compared to those identifying as white or other (mean age 65.8, 59.9, and 58.0 years respectively, p=0.0074). There were no differences in tumor receptor subtype, grade, presence of LVI, or stage by self-identified race. Black-identifying patients were significantly less likely to have the lowest ADI category (0% versus 22.6% and 20.4% in white and other categories respectively, p=0.016), and were significantly more likely to have elevated BMI (79.2% overweight/obese versus 47% of white and 41.5% of other patients, p=0.003). On univariate analysis, self-identified black race, elevated ADI, and overweight/obesity were each associated with significantly worse EFS. However, in a multivariate model containing all three predictors, only overweight/obesity remained significantly associated with worse EFS (hazard ratio 1.6, 95% confidence interval 1.1-2.3, p=0.022). Conclusions: Although prior investigators identified a relationship between non-white race and worse outcomes in patients with ILC, our data show complex relationships between many factors that impact breast cancer outcomes. The relationship between race and EFS was mitigated by ADI and obesity, suggesting that race is not an independent predictor of outcome in patients with ILC.
Citation Format: Mandeep Kaur, Anne Patterson, Julissa Molina-Vega, Harriet T. Rothschild, Elle Clelland, Mary Kathryn Abel, Laura J. Esserman, Olufunmilayo I. Olopade, Rita Mukhtar. Self-identified race and Area Deprivation Index in patients with invasive lobular carcinoma of the breast: associations with tumor characteristics and event free survival [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-08-09.