Biologic subtypes and first relapse pattern in curative surgery performed breast cancer patients: Study of Anatolian Society of Medical Oncology

e11559 Background: Relapse is one of the most important risk factors in overall survival, and distant recurrence is related to a complex biologic interaction of seed and soil factors. The aim of the study was to investigate the association between the molecular subtypes and patterns of relapse in patients with curative surgery performed breast cancer. Methods: We retrospectively evaluated clinical data from 1126 breast cancer patients with relapses after their curative surgery between 1998 and 2012 from referral centers of Turkey. Study population was divided into four biological subtypes according to their hormone receptor status and HER2 expression.Patients were divided into four biological subtypes according to IHC: triple negative (ER negative, PR negative, and HER2 negative), HER2 overexpressing (ER negative, PR negative, and HER2 positive), luminal B (ER and/or PR positive, HER2 positive), and luminal A (ER and/or PR positive, HER2 negative). Results: The proportion of patients with luminal A, Luminal B, HER2-overexpressing, and triple negative breast cancer was 42.0% (n=473), 23.0% (n=259), 13.3% (n=150), and 21,7% (n=244), respectively. Median time to relapse was 26.6 months. 22.5% of the patients (n=253) had multiple relapse sites. The incidence of first distant recurrence site was significantly different among the subtypes. Liver (31.8% vs. 22.4%, p=0.008), bone (42.2% vs 37.0%, p