The purpose of this study is to examine biological molecules in the blood that may predict the onset and severity of aromatase inhibitor-associated musculoskeletal symptoms (AIMSS). AIMSS is a condition that affects some patients who take aromatase inhibitors for the treatment of breast cancer, leading to physical discomfort and pain, which in turn can cause patients to discontinue treatment. There is evidence that biological molecules in the blood such as lipids, certain proteins, and specific types of immune cells may be linked to the onset of AIMSS. These biological molecules are referred to as biomarkers, which can also be found in other body fluids or tissues and may be a sign of a condition or disease. They can also be used to predict someone’s response to a specific treatment. In this study, researchers will examine blood biomarkers in detail to determine whether they can be used to predict AIMSS and treatment options to reduce AIMSS, thereby allowing people to take aromatase inhibitors for longer and potentially improving patient survival.