Abstract PS7-10: Hormone receptor positive breast cancers and Black race: Does gender matter?
Authors: Eskander Mariam , Li Yaming , Oppong Bridget , Bhattacharyya Oindrila , Tsung Allan , Obeng-Gyasi Samilia 
Published: February 2021

Introduction: Male breast cancer (MBC) patients present with later disease stages and have higher mortality rates than female breast cancer (FBC) patients. Additionally, black breast cancer patients, regardless of gender, consistently have worse clinical outcomes than their white counterparts. To date, there are few studies exclusively comparing clinical outcomes between black MBC and black FBC patients. The objective of this study is to understand the differences in presentation, treatment and mortality between black MBC and black FBC patients with hormone receptor positive breast cancer using the National Cancer Database (NCDB).

Methods: The NCDB was queried for all black MBC and FBC patients, ages 18-90, with hormone receptor positive breast cancer diagnosed between 2010-2016. Hormone receptor positivity was defined as estrogen receptor positive, progesterone positive and HER 2-negative cancer. Sociodemographic and clinical variables were compared between MBC and FBC patients on univariate analysis. For stages I-III patients, a propensity score (PS) was generated by a logistic regression model including the following covariates: age at diagnosis, tumor size, nodes removed, node positivity, resection margin status, hormonal treatment, chemotherapy treatment, and radiation treatment. MBC patients were matched to FBC patients using PS 2:1 nearest-neighbor matching. A log rank test was used to determine differences in survival between the matched cohort.

Results: There were 994 black MBC and 65,931 black FBC patients that met study criteria. MBC patients were older at diagnosis than women (age, MBC 63 ± 12.5, FBC 60.6± 13.3). Compared to FBC patients, more MBC patients had lower oncotype scores (RS 0-10, MBC 39.7%, FBC 24%, p&lt;0.001). Additionally, MBC patients were more likely to present with metastatic disease (stage 4, MBC 4.4%, FBC 2.6%, p&lt;0.001), had fewer smaller tumors (tumor size &lt;2cm, MBC 32.1, FBC 49.1%, p&lt;0.001) and a higher percentage of poorly differentiated tumors (grade 3, MBC 28.5%, FBC 21.4%, p&lt;0.001). Notably, MBC patients had lower rates of hormone therapy (MBC 66.4%, FBC 80.7%, p&lt;0.001) and neoadjuvant chemotherapy (MBC 5.8%, FBC 7.5%, p=0.05) utilization than their female counterparts. On propensity score matched analysis black MBC patients had a higher overall mortality compared to FBC patients (p=0.026).

Conclusion: Hormone receptor positive black MBC patients in the NCDB present with more advanced stages of disease, are less likely to receive endocrine therapy and have worse overall mortality compared to their black FBC counterparts. These results indicate that significant gender-based disparities exist in presentation, treatment and mortality among black breast cancer patients. Future studies should evaluate how biologic sex and tumor biology intersect to affect these intra-racial differences in clinical outcomes.

Citation Format: Mariam Eskander, Yaming Li, Bridget Oppong, Oindrila Bhattacharyya, Allan Tsung, Samilia Obeng-Gyasi. Hormone receptor positive breast cancers and Black race: Does gender matter? [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS7-10.