Dural metastases in breast cancer: progression pattern, treatment and prognosis-a single center experience

Background: Dural metastasis (DM) remains one of the most challenging clinical scenarios in breast cancer treatment. To date, no clear standard care of dural metastases has been established. We sought to identify the progression pattern or treatment strategies that could possibly improve prognosis of breast cancer patients with DM.

Methods: Patients with breast cancer diagnosed with radiological confirmed dural metastases excluding leptomeningeal invasion alone or meningeal invasion subsequent to brain parenchyma metastases between 2014 and 2021 in single center were reviewed. All patients underwent head-enhanced magnetic resonance imaging (MRI). Imaging information, treatment and prognostic data were recorded.

Results: A total of 66 breast cancer patients were analyzed in this study, with 50 survival status including 43 deaths. Hormone receptors positive [estrogen receptor (ER)/progesterone receptor (PR)] accounted for 43.9% of the study cohorts followed by triple-negative breast cancer (TNBC) and HER2+ subtypes successively. Most cases (34, 51.5%) were diagnosed without parenchymal brain metastases prior to or at time of DM diagnosis. Three morphological patterns were determined by MRI including nodular, thickened with nodules, and diffuse thickened types. The frontoparietal dura was the most frequently involved site, accounting for 43.9% (29/66) of the patients, followed by temporal dura and parietal dura, ranking second and third (21/66 and 15/66, respectively). Fifty-four patients had extensive bone metastasis before the diagnosis of DM, within them, the median duration from bone metastasis to the diagnosis of DM was 419 days. Forty-two patients received radiotherapy for DM, including 25 with whole brain radiotherapy (WBRT), 4 with craniospinal axis irradiation (CSI), and 13 with DM and/or brain parenchyma lesions. Multivariate analysis indicates that initial diagnosis age, brain metastasis status, neurological symptoms and systemic treatment status and are significant prognostic factors (P=0.002, 0.03, 0.02, 0.001 and 0.02, respectively). The median survival time from the diagnosis of DM was 458 days in patients who received radiotherapy compared with 225 days in patients who did not receive radiotherapy, with a hazard ratio (HR) 0.65 [95% confidence interval (CI): 0.302-1.305] and P value of 0.06. Leptomeningeal invasion, parenchymal brain metastases and number of DM-involved sites were associated with the medical decision of WBRT. There were more leptomeningeal invasion cases distributed to WBRT group (17/29 vs. 7/37, P=0.001), and a higher likelihood of concurrent parenchymal brain lesions (19/27 vs. 13/37, P=0.01).

Conclusions: Dural metastases can occur as a subsequent event in patients with poorly controlled extensive bone metastases, with the frontoparietal area being the most commonly involved site. Radiotherapeutic strategy is highly influenced by the associated metastatic volume of DM, and radiotherapy was found to improve prognosis in these patients.