PURPOSE: We aimed to investigate organ-specific recurrence or the metastatic pattern of breast cancer according to biological subtypes and clinical characteristics. METHODS: We retrospectively analyzed the medical records of 168 patients with recurrent breast cancer who were diagnosed between January 1, 2000 and April 30, 2017. Four biological subtypes were classified according to estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), and Ki-67 expression: luminal A, luminal B, HER2-enriched, and triple negative breast cancer (TNBC). To analyze recurrence patterns according to biological subtypes, we accessed clinical variables including age at diagnosis, TNM stage, type of surgery in the breast and axilla, histologic grade, nuclear grade, lymphatic, vascular, and neural invasion, Ki-67 expression and recurrence to distant organs. RESULTS: The biological subtypes of recurrent breast cancer comprised the following luminal A (n=33, 19.6%), luminal B (n=95, 56.5%), HER2 enriched (n=19, 11.3%), and TNBC (n=21, 12.5%). Luminal A (7.7%) and B (6.5%) subtypes were associated with the increased rate of local recurrence compared to HER2-enriched (2.4%) and TNBC subtypes (1.8%) (p=0.005). The bone (53.6%) was the most common metastatic organ, followed by the lung (34.5%), liver (29.8%), brain (17.9%), and other visceral organ (7.7%). Bone metastasis was commonly observed in individuals with luminal B (63.2%), HER2-enriched (57.9%), and luminal A (42.4%) subtypes (p=0.005). Most liver metastases occur in individuals with luminal B (40.0%) and HER2-enriched subtypes (31.6%) (p=0.002). CONCLUSION: Luminal B subtype was commonly observed in individuals with recurrent breast cancer, and the bone is the most common target organ for breast cancer metastasis, followed by the lungs and liver.
Axilla ; Brain ; Breast Neoplasms ; Breast ; Diagnosis ; Estrogens ; Humans ; Liver ; Lung ; Medical Records ; Neoplasm Metastasis ; Organ Specificity ; Phenobarbital ; Receptor, Epidermal Growth Factor ; Receptors, Progesterone ; Recurrence ; Retrospective Studies ; Triple Negative Breast Neoplasms