Abstract 312P
Background
Real-world outcomes of patients with breast cancer (BC) brain metastases (BrM) are poorly understood.
Methods
We conducted a retrospective, observational population-based cohort study to assess treatment patterns and outcomes of patients with BC who received radiotherapy for intracranial metastatic disease between January 2009 and December 2019. The primary endpoint was overall survival (OS) before and after adjustment for type of radiotherapy and other potential confounding variables.
Results
88,111 patients with a history of stage I to IV BC were identified, 2.4% (n=2,120) of whom required radiotherapy for BrM during their disease course. Median age at treatment was 53 (45-62). 40.4% of patients had stage I, 32.9% had stage II, 11.9% had stage III and 4.6% had stage IV disease at the time of initial BC diagnosis; stage was unknown for the remaining 10.2% of patients. The most common BC subtype was hormone receptor (HR)+/HER2- (36.9%), with 8.2% of patients having HER2+ and 5.4% having triple-negative disease; subtype was unknown in 49.6% of cases. Whole brain radiotherapy (WBRT) was administered to 82% (n=1738) of patients with BrM while 18% (n=382) were treated with stereotactic radiosurgery (SRS). The median OS from the time of radiotherapy for BC BrM was 5.4 months in the overall population. Median OS for triple-negative, HR+/HER2-, HER2+/HR- and HER2+/HR+ populations was 3.1 months, 4.8 months, 9.4 months and 11.0 months, respectively. Patients treated with SRS had a longer median OS than those treated with WBRT (9.3 months vs 4.6 months, p<0.0001), with lower 30-day mortality (5.2% vs 15.5%, p<0.001). In a multivariable Cox Model, treatment with WBRT (HR 1.76, 95%CI 1.53-2.03) and TNBC subtype (HR 1.57, 95%CI 1.34-1.85) were associated with a shorter OS after adjustment for age, Elixhauser co-morbidity index, income quintile and index year at BC diagnosis.
Conclusions
“Real world” median survival after radiotherapy for BC BrM remains poor. Given that patients treated for BrM with SRS lived longer with a lower risk of 30-day mortality than those treated with WBRT, the use of SRS should be encouraged when clinically indicated.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Dr. Katarzyna J. Jerzak.
Funding
Eli Lilly.
Disclosure
A. Sahgal: Financial Interests, Personal, Advisory Board: AbbVie; Financial Interests, Personal, Advisory Board: Merck; Financial Interests, Personal, Advisory Board: Roche; Financial Interests, Personal, Advisory Board: Varian; Financial Interests, Personal, Advisory Board: BrainLAB; Financial Interests, Personal, Advisory Board: VieCure; Non-Financial Interests, Personal, Member of the Board of Directors: International Stereotactic Radiosurgery Society (ISRS); Non-Financial Interests, Personal, Invited Speaker, co-chair: AO Spine Knowledge Forum Tumor; Financial Interests, Personal, Invited Speaker, educational seminars: Elekta AB; Financial Interests, Personal, Invited Speaker, educational seminars: Accuray Inc.; Financial Interests, Personal, Invited Speaker, educational seminars: Varian; Financial Interests, Personal, Invited Speaker, educational seminars: BrainLAB; Financial Interests, Personal, Invited Speaker, educational seminars: Medtronic Kyphon; Financial Interests, Personal, Research Grant: Elekta AB; Financial Interests, Personal, Other, Travel accommodations/expenses: Elekta; Financial Interests, Personal, Other, Travel accommodations/expenses: Varian; Financial Interests, Personal, Other, Travel accommodations/expenses: BrainLAB; Non-Financial Interests, Personal, Member: Elekta MR Linac Research Consortium; Non-Financial Interests, Personal, Member: Elekta Spine; Non-Financial Interests, Personal, Member: Oligometastases; Non-Financial Interests, Personal, Member: Linac Based SRS Consortia; Financial Interests, Personal, Research Grant: Varian. S. Das: Financial Interests, Personal, Advisory Board, Consultant: AbbVie; Non-Financial Interests, Personal, Advisory Board, Consultant: Xpan Medical; Financial Interests, Personal, Advisory Board, Consultant: Synaptive; Financial Interests, Personal, Advisory Board, Consultant: Omniscient; Financial Interests, Personal, Other, board member: Subcortical Surgery Group; Financial Interests, Personal, Invited Speaker, Past educational seminars: AbbVie; Financial Interests, Personal, Invited Speaker, Past educational seminars: Subcortical Surgery Group; Financial Interests, Personal, Invited Speaker, Past educational seminars: Congress of Neurological Surgeons; Financial Interests, Personal, Invited Speaker, Past educational seminars: Society for NeuroOncology; Financial Interests, Personal, Invited Speaker, Past educational seminars: American Association of Neurological Surgeons; Financial Interests, Personal, Research Grant, Past educational seminars: Alkerme; Financial Interests, Personal, Research Grant, Past educational seminars: Medicenna; Financial Interests, Personal, Other, Travel accommodations/expenses: Subcortical Surgery Group; Financial Interests, Personal, Other, Travel accommodations/expenses: Society for NeuroOncology; Financial Interests, Personal, Other, Travel accommodations/expenses: American Association of Neurological Surgeons; Financial Interests, Personal, Other, Travel accommodations/expenses: Integra; Financial Interests, Personal, Other, Travel accommodations/expenses: Congress of Neurological Surgeons. K.J. Jerzak: Financial Interests, Personal, Advisory Role, speaker/Consultant: Amgen; Financial Interests, Personal, Advisory Role, Speaker/Consultant: AstraZeneca; Financial Interests, Personal, Advisory Role, speaker/Consultant: Apo Biologix; Financial Interests, Personal, Advisory Role, speaker/Consultant: Eli Lilly; Financial Interests, Personal, Advisory Role, speaker/Consultant: Eisai; Financial Interests, Personal, Advisory Role, speaker/Consultant: Genomic Health; Financial Interests, Personal, Advisory Role, Speaker/Consultant: Knight Therapeutics; Financial Interests, Personal, Advisory Role, speaker/Consultant: Merck; Financial Interests, Personal, Advisory Role, speaker/Consultant: Myriad Genetics Inc; Financial Interests, Personal, Advisory Role, speaker/Consultant: Pfizer; Financial Interests, Personal, Advisory Role, speaker/Consultant: Roche; Financial Interests, Personal, Advisory Role, Speaker/Consultant: Purdue Pharma; Financial Interests, Personal, Advisory Role, Speaker/Consultant: Novartis; Financial Interests, Personal, Funding: Eli Lilly; Financial Interests, Personal, Funding: AstraZeneca. All other authors have declared no conflicts of interest.