This randomized, multi-institutional phase III trial evaluates whether routine surveillance brain MRI every 6 months improves detection and treatment characteristics of brain metastases in neurologically asymptomatic patients with stage IV breast cancer. Patients are stratified by receptor subtype, age, prior therapy, and study site, then randomized 1:1 to either scheduled surveillance MRIs or standard-of-care symptom-triggered imaging. The study aims to determine whether earlier detection leads to differences in treatment modality, frequency of brain metastases, leptomeningeal disease incidence, quality of life, and survival outcomes.

Inclusion Criteria:

• Histologic diagnosis of breast cancer with documentation of ER/PR/HER2 status
• Radiographic evidence of stage IV extracranial disease enrolled within 60 days of diagnosis or starting first line therapy. HR+/HER2- patients may be enrolled within 60 days of starting 2nd line therapy as well.
• HR+ will be defined as ER and/or PR > 10%. To be classified as HER2+ disease, overexpression of HER2 by either IHC or in-situ hybridization is necessary as defined by the ASCO / CAP Guidelines41. Triple negative will be classified as ER and PR <10% and HER2-.
• Age ≥ 18
• Life expectancy ≥ 6 months
• Eastern Cooperative Oncology Group performance status ≤ 2
• Patients must be able to understand and the willingness to sign an informed consent for study procedures
• Stated willingness to comply with all study procedures and availability for the duration of the study

Exclusion Criteria:

• Prior diagnosis or treatment of brain metastases or leptomeningeal disease
• History of other non-breast malignancy requiring treatment with the exception of those with a negligible risk of metastasis or death (e.g., 5-year OS of > 90%), such as but not limited to, non-melanoma skin cancers, stage I endometrioid uterine cancer, and others at the discretion of the PI
• Neurologic symptoms warranting standard screening brain MRI in the judgement of the treating physician at time of enrollment
• Indications warranting brain MRI for other neurologic conditions at time of study entry (including multiple sclerosis, stroke, traumatic brain injuries, epilepsy, hydrocephalus and pituitary gland disorders)
• Contraindication towards MRI with contrast
• Chronic kidney disease stage IV or V or end stage renal disease (CrCl <30 ml/min)