ESR1 and breast cancer: Some of the reviewed biomarkers have strong prognostic potential, allowing earlier determination of disease progression (APC, RASSF1, ESR1, TMEM240), association with BC stage (GBP2, RASSF1, APC, PTEN, SMAD4), lymph node metastasis (GBP2, ESR1, PTEN) or poor differentiation grade (ESR1, RASSF1, SMAD4).