P3-03-01: Low Expression of Microrna-210 is an Independent Good Prognostic Factor in Japanese Triple-Negative Breast Cancer Patients.

Abstract Background: microRNAs (miRNAs) have emerged as a new class of non-coding genes involved in regulating cell proliferation, differentiation, and viability. Recent studies have identified miR-210 among a set of hypoxia-regulated miRNAs and demonstrated a direct regulatory role of hypoxia-inducible factor-1 alpha (HIF-1 a) in its transcription. High expression of miR-210 has been reported to be a poor prognostic factor in several types of cancers including breast. Materials and Methods: TaqMan MicroRNA assays for miR-210 expression were performed in 219 breast cancers (58 triple-negative (TNBCs), and 161 ER-positive and HER2−negative). Correlations between miR-210 expression and clinicopathological factors were analyzed. The effects of several variables on survival were tested by Cox proportional hazards regression analysis. Results: miR-210 expression in TNBCs was significantly higher than in ER-positive and HER2−negative breast cancers (p<0.001). Patients whose TNBCs had low miR-210 expression experienced significantly better disease-free and overall survival compared with high miR-210 expressors (p=0.02 and p=0.05, respectively). Notably, among 40 node-negative TNBCs, 5-year disease-free survival was approximately 60% in patients whose tumors had high or intermediate miR-210 expression (n=26), while no patients with low miR-210 expression (n=14) suffered recurrent disease. Cox univariate and multivariate analyses demonstrated that low expression of miR-210 was an independent good prognostic factor in TNBCs. Discussion: Although prognosis of patients with TNBCs is poor, those whose tumors expressed low levels of miR-210 had a more favorable prognosis. Thus, the degree of miR-210 expression might be a clinically useful prognostic factor for decision-making regarding treatment in the adjuvant setting, especially in node-negative TNBC patients. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-03-01.