Spearman correlation analysis of breast cancer subgroups revealed that the association between nuclear Cyclin E and γ-H2AX expression was strongest in ER/PR−HER2+ (Table 1, r = 0.86, P < 0.001) and TNBC (Table 1, r = 0.71, P < 0.001). Here, CCNE1 is linked to breast cancer.