Tirzepatide's Role in Postmenopausal HR+ Breast Cancer Survivors

Inclusion Criteria: * Biologically female * Age ≥ 18 * Obesity as defined by current BMI ≥ 30 kg/m² or ≥ 27.5 kg/m² for individuals of Asian ancestry * Postmenopausal as defined by one or more of the following * Age ≥60 years * Age \<60 years with amenorrhea for ≥ 1 year * Documented bilateral surgical oophorectomy * Chemical menopause with the addition of LHRH agonists at least 12 weeks prior to enrolment, and plan to remain on LHRH agonists throughout the trial * HR+ (ER and/or PR) stage 0-III breast cancer * Completed curative treatment (surgery, chemotherapy, radiotherapy) at least 12 weeks prior to enrolment * Insurance approval for tirzepatide or willing to pay out of pocket * Willing to provide informed consent and comply with study procedures Exclusion Criteria: * Stage IV breast cancer * Concomitant use of CDK inhibitors * Concomitant use of antiHER2 therapy * The PI may be consulted regarding enrollment of females receiving other endocrine therapy medications * Other active malignancy requiring treatment * Enrollment in another investigational clinical trial * Contraindication to tirzepatide * Treatment with a GLP-1 receptor agonist within the last 3 months * Diabetes requiring insulin * Any disorder, unwillingness, or inability, not covered by any of the other exclusion criteria, which in the investigator's opinion, might jeopardize the subject's safety or compliance with the protocol