P3-04-04: Patterns of Distant Metastasis According to the Molecular Subtypes of Breast Cancer; Results of 529 Breast Cancer Patients.

Abstract

Abstract Backgrounds; Distant metastasis from breast cancer arises from various sites. But few studies concerning factors that can predict metastasis patterns in breast cancer has been reported. In this study, we analyzed the effect of breast cancer molecular subtypes on distant metastasis patterns and tried to determine factors that predict metastasis sites. Patients and methods; From January 1995 to January 2004 at Yeungnam university hospital, patients diagnosed with the primary invasive breast cancer and received treatments were included in this study. Patients with bilateral breast cancer or distant metastasis at diagnosis were excluded. After analyzing estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), epidermal growth factor (EGFR) and cytokeratin (CK) 5/6 status, we classified patients into 5 categories, luminal A, luminal B, HER2−enriched, basal-like, and normal (triple negative nonbasal) breast cancers. Distant metastatic patterns of each category were analyzed. Results; 529 patients were eligible for tissue microassay analysis and median follow-up period was 7.7 years. In this period, total 82 patients (15.5%) had locoregional relapse or distant metastasis and distant metastasis were identified in 54 patients (10.2%). Each distant metastatic rate was 10.5% (33/313) in luminal A, 8.7% (4/46) in luminal B, 10.2% (6/59) in HER2−enriched, 7.9% (7/89) in basal-like, and 18.2% (4/22) in normal subtype. Most frequent site of distant metastasis in all patients was bone and such result was consistent with Luminal A subtype. Liver metastasis was most frequent in Luminal B subtype, lung metastasis in HER2 enriched and normal subtype and brain metastasis in basal-like subtype. Conclusions; There was a definite association between breast cancer molecular subtype and distant metastatic pattern. If more patients and prolonged follow up periods are analyzed, we would be able to determine the best follow up intervals, methods and treatment directions concerning subtypes of breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-04-04.