Lack of histopathologic characterization of BCLM tumors further limits development of targeted therapeutics. Methods: We collected BCLM tissues from 47 OHSU breast cancer patients who underwent liver biopsy/surgical resection for clinical indications of liver metastases. High GATA3 staining was observed in 86% of BCLM, supporting luminal cell origin. At primary breast cancer diagnosis, 85% of the primary tumors were ER+, 60% luminal A, 57% low grade, and 73% early stage. Improved understanding of the dominant replacement growth pattern and the interaction between tumor cells and the liver sinusoids may lead to new drug targets and precision therapies.
