ESR1 and breast cancer: ROC curves of serum exo-AnxA2 in breast cancer subtypes showed that AUC values of ER+, HER2+, and TNBC were 0.8304 ± 0.03843 (95% CI 0.7551–0.9058, P < 0.0001), 0.9958 ± 0.0029 (95% CI 0.9899–1.000, P < 0.0001) and 1.000 ± 0.000 (95% CI 1.000–1.000, P < 0.0001), respectively (Fig. 7b).