To access possible relationships between breast cancer subtypes (BCS) and patterns of distant metastasis in advanced breast cancer. Breast cancer patients with distant metastasis at two academic centers from 2000-2015 were retrospectively reviewed. The breast cancer was classified into four subtypes: hormone receptor (HR) +/ human epidermal growth factor receptor 2 (HER2) - (i.e., estrogen receptor [ER] + and/or progesterone receptor [PR] +, HER2-); HR+/HER2+ (ER+ and/or PR+, HER2+), HR-/HER2+ (ER- and PR-, and HER2+); and HR-/HER2- (ER- and PR-, and HER2-). A total of 679 patients were identified. The distribution of the BCS was 39.9% (271/679), 23.7% (161/679), 16.8% (114/679), and 19.6% (133/679) in HR+/HER2-, HR+/HER2+, HR-/HER2+, and HR-/HER2-, respectively. Patients with HR+/HER2+ and HR-/HER2+ subtypes were prone to abdominal and pelvic metastasis, those with HR+/HER2- and HR+/HER2+ subtypes were prone to bone metastasis, while patients with the HR-/HER2- subtype were prone to lung/mediastinal and brain metastases. In patients with pleural, axillary and/or neck lymph node, and other distant soft tissue metastases, there was no significant difference in metastatic patterns among the BCS. There are different patterns of distant metastasis associated with different BCS. There should be a different focus in the postoperative follow-up and monitoring of breast cancer patients with different BCS.
Keywords: breast cancer; breast cancer subtype; distant metastasis; patterns.