ESR2 and breast cancer: Furthermore, the impact of the MET gene on disease characteristics was dependent on its partner ESR gene in our study, and it revealed a striking difference when MET expression was associated with ESR1 or ESR2. Together, these findings provide a rationale for risk stratification and treatment of breast cancer patients based on gene expression of MET and ESR. The increased expression of MET/ESR2 genes in younger patients with breast cancer may explain the aggressive phenotype and the advanced tumor characteristics that collectively impose a worse prognosis in this group of patients.