miR-320a is an independent prognostic biomarker for invasive breast cancer

Breast cancer is one of the most common malignancies worldwide and is the second leading cause of cancer-related mortality among females. miRNAs are a class of small noncoding RNAs that are aberrantly expressed in human cancers. Due to their small size and stability, miRNAs have the potential to be efficacious clinical targets. MicroRNA-320a (miR-320a) has been shown to be dysregulated in multiple malignancies. In the present study, the expression levels of miR-320a were investigated in 15 paraffin-embedded in situ breast carcinoma and 130 invasive breast cancer tissues, and the prognostic value for breast cancer patients was assessed. Chromogenic in situ hybridization revealed that 60/130 (46%) invasive breast cancer tissues exhibited high expression levels of miR-320a (staining index score of ≥4). Furthermore, miR-320a staining was found to significantly correlate with tumor size (P=0.046), clinical stage (P