PLK1 over-expression was observed in 27.4% (410/1494) of cases (Figure 1A), and this was found to be significantly correlated with adverse clinico-pathological parameters such as older age (p = 0.0046), poorly differentiated tumors (p < 0.0001), ER negative (p < 0.0001), PR negative (p = 0.0017), triple negative breast cancer (p < 0.0001) and high proliferative index (Ki-67; p < 0.0001) (Table 2). Here, ESR1 is linked to triple-negative breast carcinoma.