ESR1 and obstructive sleep apnea syndrome: Patient is a 63-year-old female with a past medical history significant for stage IV invasive ductal carcinoma, positive for estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2), with osseous metastases to the calvarium and ribs, heart failure with preserved ejection fraction, diabetes mellitus type 2, hypertension, obstructive sleep apnea, unspecified anxiety disorder, and recurrent major depressive disorder.