Outcomes of ER, PR, HER2, and triple-negative mutated breast cancer with brain metastasis.

Abstract

e14009 Background: Breast cancer is the second most common cause of metastatic brain tumors. The presence of estrogen receptors (ER), and progesterone receptors (PR), and HER2 receptors have been used to guide both hormonal and targeted therapies for breast cancer. The presence or absence of these receptors may impact patient outcomes in breast cancer brain metastasis (BCBM). Methods: Patients with BCBM and known tumor marker status treated at our tertiary care center from 2010-2019 were evaluated. Overall Survival (OS) was measured from diagnosis of BCBM to date of death or last follow up. Many of these patients received multiple lines of treatment including hormonal and targeted therapies at some point during their care. The Cox proportional hazard model was used to determine differences in OS. Results: 137 patients with BCBM were included. Of these, 48 were ER or ER/PR positive (ER+), 3 were PR positive (PR+), and 47 were HER2, HER2/PR, HER2/ER, or HER2/ER/PR positive (HER2+), and 37 were triple-negative. For ER+ tumors the median age at diagnosis was 60 years (Interquartile range (IQR) 31-87) and 86% were white. For PR+ tumors the median age at diagnosis was 67 years (IQR 66-74) and 75% were white. For HER2+ tumors the median age at diagnosis was 55 years (IQR 31-84) and 79% were white. For triple-negative tumors the median age at diagnosis was 56 years (IQR 34-91) and 83% were white. OS for ER+, PR+, HER2+, and triple-negative patients had a median of 57.7, 19.8, 137.4, and 54.6 months and a 2-year rate of 76%, 33%, 82%, and 73%, respectively. With ER+ patients as a reference, PR+ patients had an OS hazard ratio of 1.49 (95% CI = 0.35 - 6.23, p = 0.59), HER2+ patients had an OS hazard ratio of 0.62 (95% CI = 0.36 - 1.06, p = 0.082), and triple-negative patients had an OS hazard ratio of 0.92 (95% CI = 0.54 - 1.57, p = 0.77). Conclusions: HER2+ tumors were associated with an increase in OS when compared to ER+, PR+, and triple-negative tumors in patients with BCBM. The OS of the other three tumor marker groups was not significantly different from one another. Further studies need to be done within tumor marker cohorts to determine the most effective treatments within those cohorts.[Table: see text]