Abstract P4-03-21: Racial disparities in survival trends in patients with metastatic Hormone receptor positive/Her 2 negative breast cancer: a SEER population-based study
Authors: Soto Alvaro Alvarez , Bernal Ana Maria , Mesias Jesus Anampa 
Published: March 2023

Abstract
Hormone-receptor-positive (HR+) breast cancer (BC) accounts for around 70% of all BCs[1]. Targeting the estrogen-receptor (ER) pathway has been the therapeutic focus; however, a substantial subset of HR+ BCs are resistant to hormonal blockade. Addition of Cyclin-dependent kinases 4 and 6 inhibitors (CDKis)to endocrine therapy has demonstrated to improve progression-free and overall survival in patients with metastatic ER+ BC. However, these trials enrolled mostly non-Hispanic White patients, with minimal inclusion of non-Hispanic Black and Hispanic patients. The goal of this study is to assess survival trends for different racial/ethnic groups in patients with HR+ HER2- BC before and after introduction of the CDKis as standard of care (year 2015). Methods: Using the SEER database of the National Cancer Institute, we identified patients with metastatic HR+ HER2- breast cancer. We obtained patients with ICD-0-3 codes 8500/3, 8501/3, 8502/3, 8503/3, 8507/3, 8520/3, 8521/3, 8522/3, 8523/3 and 8524/3. We divided them in two time-based cohorts: patients diagnosed in 2010-2013 and patient diagnosed in 2015-2018. SEER*STAT and Kaplan-Meir methods were used to estimate breast cancer specific survival at 6, 12, 24, 36 and 48 months for each group. Trends in survival were compared among Hispanic (H), Non-Hispanic White (NHW), and Non-Hispanic Black (NHB) patients. Results: We identified 10,019 patients that met our inclusion criteria, 4,667 (47%) diagnosed during 2010-2013 and 5,352 (53%) diagnosed during 2015-2018. For the patients diagnosed during 2010-2013, there were 4610 (99%) female and 57 (1%) were male. In the 2010-2013 group non-Hispanic white patients were 3,124 (67%) vs. 3,443 (64%) in 2015-2018, Non-Hispanic black patients were 639 (14%) vs. 736 (14%) and 521 (11%) vs. 645 (12%) were Hispanic of any race. For the 2010-2013 group, 3,463 (74%) had bone, 884 (19%) liver, 239 (5%) brain and 1,222 (26%) lung metastasis. There were 3,830 (83%) ER+/PR+ tumors, 777 (17%) ER+/PR- and 60 (1%) ER-/PR+. For the 2015-2018 group, there were 5266 (98%) female and 86 (2%) were male. 4011 (75%) had bone, 961 (18%) liver, 257 (4%) brain metastasis and 1469 (27%) lung metastasis. There were 4,424 (82%) ER+/PR+ tumors, 876(16%) ER+/PR- and 52 (1%) ER-/PR+. The 48-month BCSS rate for all patients improved from 2010-2013 to 2015-2018 (46.3% vs. 40.2 %), with an absolute improvement in 7.4%, 1.4%, 3.6% for NHW, NHB, and H patients, respectively. The 36-month BCSS rate for all patients improved from 2010-2013 to 2015-2018 (55.6% vs. 51.3%), with an absolute improvement in 4.9%, 2.6% for NHW, H patients, respectively, whereas NHB showed an absolute decrease of 4.5%. The 12-month BCSS rate for all patients improved from 2010-2013 to 2015-2018 (81.5% vs. 80.2%), with an absolute improvement in 2.4% and 0.8% for NHW, and H patients respectively. For NHB there was an absolute decrease in survival of 2.4%. Conclusions: Using population data, we report that the 48-month BCSS has improved from 2010-2013 to 2015-2018 by about 5.9%. However, the magnitude of the improvement was different by racial/ethnical groups. The magnitude of improvement in BCSS is higher in NHW as compared to NHB and H patients. Our results suggest that despite recent advancements in the management of ER+/HER2- metastatic BC, racial disparities in outcomes still persist which could be explained by either intrinsic genetic differences in response to novel agents or lack of access to them in some ethnical/racial groups.
Citation Format: Alvaro Alvarez Soto, Ana Maria Bernal, Jesus Anampa Mesias. Racial disparities in survival trends in patients with metastatic Hormone receptor positive/Her 2 negative breast cancer: a SEER population-based study [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 P4-03-21.