To explore the prognostic and predictive value of SLC7A5/SLC3A2 co-expression in ER+/HER2− breast cancer at the mRNA and protein levels, the cases were divided into four categories (SLC7A5−SLC3A2−, SLC7A5+SLC3A2−, SLC7A5−SLC3A2+ and SLC7A5+SLC3A2+). The gene discussed is SLC3A2; the disease is breast cancer.