CYP19A1 and breast cancer: The ESR1-AKAP12 fusion was identified in 6.5% breast cancer that were resistant to letrozole aromatase inhibitor treatment [17].The novel fusion ESR1-ARMT1 was instead detected in a HER2-negative patient with luminal A-like subtype [16] and in a breast cancer patient who had not received endocrine therapy [18].