ESR1 and triple-negative breast carcinoma: Triple-negative breast cancer (TNBC) is considered one of the most severe subtypes, accounting for 10%–20% of breast cancer diagnoses, and is defined by the lack of expression of the estrogen receptor (ER), progesterone receptor (PR), and HER2 (Zhao et al., 2021; Abu-Jamous et al., 2017).