Abstract P4-05-13: Prognostic implication of Yin Yang 1 (YY1) overexpression in patients with primary breast cancer

Abstract

Abstract Background: YY1 is conserved transcriptional factor that highly expressed in various types of cancers. It regulates differential epigenetic pathways and protein modifications. However, there is still unknown whether YY1 overexpression has any prognostic significance in breast cancer patients. In this study, we evaluated YY1 expression levels using tissue microarrays and analyzed clinicopathologic characteristics with survival outcomes. Methods: Clinical information and tissue blocks were obtained retrospectively from 491 patients who underwent surgery at Hanyang University Hospital between 2002 and 2016. Immunohistochemical staining was performed using rabbit monoclonal antibody (ab-109237). YY1 expression was determined using H-score. Overexpression was defined as H-score ≥ 28.4 (mean value). Overall survival (OS) and disease-free survival (DFS) was analyzed by Kaplan Meier analysis. Results: Of 491 patients with primary breast cancer, 138 (28.1%) patients had YY1 overexpression. Luminal subtype (ER+/HER2-), early tumor stage, and low grade tumor were significantly associated with overexpression (P<0.0001). In patients with luminal subtype, overexpression was significantly correlated with early nodal stage and low proliferation index (Ki-67≤20%, P=0.014). After median follow up 67 months, YY1 overexpression was significantly associated with better prognosis (OS rates; 96.4% vs. 88.1%, P=0.038 and DFS rates; 92.0% vs. 79.2%, P=0.014). In luminal subtype, patients with overexpression showed better DFS (93.0% vs. 80.2%, P=0.043). In a Cox proportional hazards model, YY1 overexpression was independent significant prognostic factor after adjustment of ER/HER2 status and tumor size (hazard ratio; 0.5, 95% CI [0.26-0.98], P=0.042). Conclusion: YY1 overexpression is a better prognostic marker in patients with primary breast cancer, especially in luminal subtype. Citation Format: Chihwan Cha, Hosub Park, Chul Geun Kim, Min Sung Chung. Prognostic implication of Yin Yang 1 (YY1) overexpression in patients with primary breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-05-13.