Real-world outcomes of metastatic invasive lobular ductal breast cancer in the German prospective OPAL research platform

Evidence about routine treatments and outcomes of patients with invasive lobular breast cancer is limited, especially regarding metastatic disease. Analysis of the prospective OPAL research platform in Germany investigated real-world outcomes of patients with metastatic invasive lobular cancer (mILC) as compared to metastatic invasive ductal cancer (mIDC). Compared to mIDCs, patients with mILC were older at start of first-line treatment, and had more often lower grade, HR-positive and less often HER2-positive tumors, which metastasized more frequently to the bone or peritoneum and less frequently to the lungs. The median overall survival was 33.7 months in the mIDC group versus 30.2 months in the mILC group. Multivariate analysis did not show a significant impact of histological subtype on survival (mILC versus mIDC HR 1.18; 95% CI 0.97-1.42). The authors conclude that despite mILC patients presenting with some favorable prognostic factors, ILC histopathology was not associated with better clinical outcome, suggesting the need for more tailored treatment strategies for mILC.