Disparities in patients with HER2-positive breast cancer receiving optimal treatment: Analysis of the real-world ASCO CancerLinQ dataset.

person Olga Kantor Brigham and Women's Hospital, Boston, MA info_outline Olga Kantor, Alyssa N Jones, Erica L. Mayer, Mariana Chavez-MacGregor, Tari A. King, Elizabeth A. Mittendorf

Authors person Olga Kantor Brigham and Women's Hospital, Boston, MA info_outline Olga Kantor, Alyssa N Jones, Erica L. Mayer, Mariana Chavez-MacGregor, Tari A. King, Elizabeth A. Mittendorf Organizations Brigham and Women's Hospital, Boston, MA, Dana-Farber Cancer Institute, Boston, MA, The University of Texas MD Anderson Cancer Center, Houston, TX Abstract Disclosures Research Funding Dana-Farber Susan F. Smith Innovation Award Background: Racial/ethnic disparities in locoregional second breast cancer events (SBCE) in patients (pts) with HER2-positive (HER2+) breast cancer (BC) are not well defined. We examined rates of SBCE and overall survival (OS) by race and ethnicity in the ASCO CancerLinQ Discovery (CLQD) real-world dataset in HER+ BC pts receiving optimal and not-optimal treatment. Methods: CLQD was used to identify pts undergoing surgery for stage I-III HER2+ BC from 2005-2022. Race/ethnicity were self-reported. Optimal treatment was defined as HER2-directed therapy for stage II-III HER2+ BC starting in 2008, adjuvant endocrine therapy for hormone-receptor positive (HR+) HER2+ BC, radiation after lumpectomy, and regional nodal irradiation for N2-N3 disease. The primary endpoint was SBCE defined as a second event in the ipsilateral or contralateral breast or axilla, with OS as a secondary endpoint. Kaplan-Meier analysis was used to estimate SBCE-free survival and OS. Results: Of 8,795 stage I-III HER2+ BC pts, 5,487 (62.4%) were Non-Hispanic White (NHW), 1,083 (12.3%) Non-Hispanic Black (NHB), 418 (4.7%) Hispanic, 323 (3.7%) Asian or Pacific Islander (API), and 1,484 (16.9%) other/unknown. Overall, 39.2% had HR-HER2+ and 60.7% had HR+HER2- BC. NHW pts were the most likely to present with stage I disease (40.2% vs 31.9%, 29.0%, and 30.3% of NHB, Hispanic, and API pts, respectively, p<0.01) and less likely to be age <50 at diagnosis (26.1% vs 32.3%, 41.0%, and 36.6% in NHB, Hispanic, and API, p<0.01). Overall, 54.2% of HER2+ BC pts received optimal treatment: 54.1%, 60.2%, 60.5%, and 58.8% of NHW, NHB, Hispanic, and API pts (p<0.01). Neoadjuvant HER2-therapy was given in 42.4%, 46.3%, 53.8%, and 51.2% of NHW, NHB, Hispanic, and API pts (p<0.01) and endocrine therapy in 64.7%, 56.8%, 59.3%, and 54.7%, respectively (p<0.01). 5-yr SBCE-free survival and OS are shown (Table). SBCE-free survival was not statistically different by race and ethnicity in optimally or non-optimally treated pts. Optimal treatment increased OS by 4.1% and 0.9% in NHW and NHB pts with HR-HER2+ BC and 2.4% and 8.9% in NHW and NHB pts with HR+HER2+ BC. Conclusions: Differences in OS, but not SBCE, were seen by race/ethnicity in HER2+ BC. OS differences were not completely mitigated by receipt of optimal treatment. 5-yr estimated SBCE-Free and OS by race/ethnicity. NHW NHB Hispanic API P-value Events 5-yr % Events 5-yr % Events 5-yr % Events 5-yr % HR-HER2+ SBCE-Free Survival Optimal Not Optimal 20 13 97.4 97.4 3 2 98.8 98.1 0 0 100 100 0 1 100 96.9 0.11 0.85 HR+HER2+ SBCE-Free Survival Optimal Not Optimal 21 12 98.6 98.7 9 4 97.1 97.5 5 1 95.4 98.3 1 1 98.9 98.2 0.07 0.16 HR-HER2+ OS Optimal Not Optimal 86 74 89.8 85.7 29 15 87.7 86.8 2 2 97.3 94.5 1 0 98.8 100 0.01 0.02 HR+HER2+ OS Optimal Not Optimal 95 78 93.6 91.2 12 21 96.2 87.3 8 2 93.4 97.3 1 1 98.9 98.1 0.08 0.04