Abstract PD7-05: Survival of patients with brain metastases at initial breast cancer diagnosis over the last decade
Authors: Avila Jorge , Leone Julieta , Vallejo Carlos T. , Lin Nancy U. , Leone Jose P. 
Published: March 2023

Abstract
Background
Brain metastases (BM) is a challenging presentation of breast cancer (BC) and has historically been associated with poor prognosis. The risk of BM is higher in patients (pts) with hormone receptor (HR) negative, human epidermal growth factor receptor 2 (HER2)-positive, or triple negative (TN) tumors.
There have been significant advances in the treatment of metastatic BC over the past several years, and long-term outcomes after a diagnosis of breast cancer brain metastases (BCBM) are lacking; therefore, this study aimed to identify clinical predictors of BM at initial BC diagnosis, to describe trends in overall survival (OS) over the past decade, and to identify factors associated with OS after BM diagnosis.
Methods
We evaluated pts with de novo stage IV BC using the Surveillance, Epidemiology and End Results (SEER) database from 2010-2019. A multivariate logistic regression model was conducted among all pts with stage IV BC to assess predictors of BM at initial BC diagnosis. OS probabilities were estimated using the Kaplan-Meier method and log rank test was used to compare differences between groups. Among pts with BM at initial BC diagnosis, univariate analyses were performed to determine the effects of each variable on OS. A Cox proportional hazards regression was used to assess the independent association of several variables with OS.
Results
A total of 425,110 pts with BC were identified from 2010-2019; 25,113 had stage IV BC at diagnosis and among these, 1,939 pts had BM at initial BC diagnosis. For this last group median age was 60 years and median follow up was 54 months.
We performed a logistic regression model to evaluate the factors correlated with BM at initial BC diagnosis among all stage IV BC pts and found that lobular vs ductal histology (OR 0.68; 95% CI 0.55-0.85), HR-/HER2+ vs HR+/HER2- tumors (OR 1.93; 95% CI 1.64-2.29), and the presence of bone (OR 1.19; 95% CI 1.07-1.32), liver (OR 1.25; 95% CI 1.12-1.39), lung (OR 1.72; 95% CI 1.55-1.89), or lymph node (OR 1.21; 95% CI 1.03-1.42) metastases, were significantly associated with this presentation.
The table shows OS by tumor subtype among all pts with BM at initial BC diagnosis, as well as the survival rate at 2, 5 and 8 years. We observed significant differences in survival by tumor subtype, where pts with HR+/HER2+ disease had the longest OS (median 18 months; 95% CI: 13-22 months; p = &lt; 0.0001) and the highest rate of OS at 8 years (12.2%; 95% CI 7.61%-17.95%). In contrast, TN BC had a median OS of 6 months (95% CI 5-8 months) and a rate of OS at 8 years of 2.57% (95% CI 0.1%-5.48%).
Multivariate analysis among pts with BM at initial BC diagnosis revealed differences in OS in those who were &gt;64 years vs &lt; 50 years (Hazard Ratio [HzR] 1.51; 95% CI 1.29-1.77), married vs single (HzR 0.79; 95% CI 0.70-0.91), lower vs higher income (HzR 1.45; 95% CI 1.19-1.76), tumor grade III/IV vs grade I (HzR 1.68; 95% CI 1.24-2.28), TN subtype vs HR+/HER2- (HzR 2.13; 95% CI 1.81-2.49), as well as pts with additional liver (HzR 1.34; 95% CI 1.20-1.51) or lung metastases (HzR 1.34; 95% CI 1.20-1.49).
We did not observe significant changes in OS over time (adjusted HzR 0.996 per year; 95% CI: 0.96-1.02, p = 0.837).
Conclusions:
Over the last decade, the median OS of pts with BM at initial BC diagnosis has remained poor. However, a substantial minority of pts survive 5 or more years, with long-term survival rates higher in pts with HER2+ tumors. In addition to tumor subtype, OS varied according to age, the presence of metastases to other organs, and sociodemographic factors.

Citation Format: Jorge Avila, Julieta Leone, Carlos T. Vallejo, Nancy U. Lin, Jose P. Leone. Survival of patients with brain metastases at initial breast cancer diagnosis over the last decade [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 PD7-05.