Abstract P1-09-01: African American women have lower pathologic complete response rates to neoadjuvant chemotherapy compared to white women for triple negative and HER 2 positive breast cancer
Authors: Killelea BK , Chagpar AB , Horowitz NR , Pusztai L , Wang S , Mougalian S , Lannin DR 
Published: May 2016

Introduction

Although racial disparities in breast cancer treatment have been well documented, data regarding differences in response to neoadjuvant chemotherapy are few. In 2010 the National Cancer Database (NCDB) included a new variable, documenting pathologic complete response (pCR) after neoadjuvant chemotherapy. The purpose of this study was to explore racial differences in the rates of pCR by molecular subtype.

Methods

The NCDB was queried to identify women diagnosed with invasive, stage 1-3 breast cancer in 2010 -2011 who received neoadjuvant chemotherapy. Univariate and multivariate logistic regression was performed to determine factors associated with likelihood of pCR.

Results

Out of 278,815 patients with known race and ethnicity, 27,300 (10%) received neoadjuvant chemotherapy. Of 17,970 where the outcome was known, 5,944 (33%) had a pCR. As seen in the table, there were no differences in response rate for ER/PR+ tumors, but compared to whites, non-hispanic black women had a lower rate of pCR for ER/PR- Her2+ and triple negative tumors. This difference persisted when adjusted for patient age, clinical T stage, clinical N stage, histology, grade, comorbidity index, facility type, geographic region, insurance status, and census-derived median income and education for the patient's zip code (OR 0.84, 95% CI: 0.77-0.93).

pCR rate by race and molecular subtype RacepCR number (%)p valueER/PR+, Her 2-Non-Hispanic White943/5129 (18.4%)reference Non-Hispanic Black204/1042 (19.6%)0.367 Non-Hispanic Asian/Pacific Islander59/291 (20.3%)0.420 Hispanic121/609 (19.9%)0.373ER/PR+, Her 2 +Non-Hispanic White852/2107 (40.4%)Reference Non-Hispanic Black143/380 (37.6%)0.304 Non-Hispanic Asian/Pacific Islander42/124 (33.9%)0.148 Hispanic92/224 (41.1%)0.854ER/PR-, Her 2 +Non-Hispanic White698/1295 (53.9%)Reference Non-Hispanic Black116/272 (42.6%)0.001 Non-Hispanic Asian/Pacific Islander66/112 (58.9%)0.306 Hispanic88/174 (50.6%)0.409ER/PR-, Her 2-Non-Hispanic White1318/3079 (42.8%)Reference Non-Hispanic Black416/1138 (36.6%)&lt;0.001 Non-Hispanic Asian/Pacific Islander64/165 (38.8%)0.310 Hispanic159/381 (41.7%)0.689

Conclusions

Non-hispanic black women have a lower likelihood of pCR after neoadjuvant chemotherapy compared to white women for triple negative and Her 2 positive breast cancer. It is unknown whether this is due to biologic differences in chemosensitivity or whether it represents treatment or socioeconomic differences that cannot be adjusted for in the current analysis.

Citation Format: Killelea BK, Chagpar AB, Horowitz NR, Pusztai L, Wang S, Mougalian S, Lannin DR. African American women have lower pathologic complete response rates to neoadjuvant chemotherapy compared to white women for triple negative and HER 2 positive breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-09-01.