Assessing The Rate Of Brain Metastases And Utility Of Brain Mris In Patients With Locally Advanced Breast Cancer

Brain metastases (BMs) remain a major cause of morbidity and mortality for patients with breast cancer (BC). Currently, the NCCN guidelines do not recommend routine screening for BMs using MRI in patients without symptoms. However, with advanced radiation therapy (such as SRS) and novel systemic agents, early detection of BMs presents an opportunity to successfully treat these patients without incurring the morbidity and mortality of advanced intracranial disease. This study investigated the rate of positive brain MRIs in Locally Advanced Breast Cancer (LABC) patients at high risk for metastatic recurrence in hopes to better identify screening strategies. A retrospective review of patients with Stage III (AJCC 8th edition) BC who completed definitive trimodality therapy at a safety-net hospital between 2008 and 2019 was conducted. Of those, patients who underwent brain MRI were identified. Patient, tumor, and treatment characteristics were recorded as well as time from diagnosis to MRI, time from completion of therapy to MRI, radiology findings and management. A total of 100 women were identified, 31 of whom underwent a cumulative of 39 MRIs (6 prior to, 7 during, and 26 post-treatment). In most (77%) of the cases, the indication for imaging was prompted by neurological symptoms. All 13 MRIs done prior to or during treatment were negative. Twenty-five patients underwent a total of 26 post-treatment MRI (ptMRI), 6 of which were positive: 2 with calvarial and 4 with symptomatic intracranial mets (1 with leptomeningeal disease and 3 with diffuse BMs). All 4 had locoregional or distant progression within a year before developing BMs. Two were hormone receptor positive (HR)+ (ER+PR+/H2N- and ER+PR-/H2N+) and with nearly twice the average time from diagnosis to ptMRI (60.7 vs 32.1 months) compared to the 2 HR- women (triple negative and ER-PR-/H2N+). Only the HR+ patients were fit to undergo palliative whole brain radiation (30Gy in 10 fractions), and all 4 died within 2 months of their ptMRI. Even in the high-risk sample studied, pre-treatment brain MRI even with neurological symptoms had low likelihood of identifying BMs. However, ptMRI had approximately 1 in 6 chance of identifying significant BM, with HR+ patients taking longer to manifest than HR- patients, likely owing to less aggressive biology and benefits of endocrine therapy. All BMs were found within a year of an extracranial progression event. Unfortunately, all of the cases were advanced and failed attempted salvage. The results are hypothesis-generating, and suggest screening MRI at the time and within a year of extracranial progression may lead to early detection of salvageable, asymptomatic BMs.