YB-1 is a high risk factor in low-risk patients. YB-1 is expressed in 34% (437/1292) of low-risk patients who received no systemic therapy. 'N' represents the number of patients who died from breast cancer (number of events) in each category. Survival was stratified based on whether tumors expressed YB-1 (light grey line) or did not (black line). YB-1, Y-box binding protein-1.