Your genes may decide if breast cancer drug causes joint pain

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Patients must be post-menopausal; post-menopausal will be defined as women meeting any of the following criteria: * \>= 60 years of age; or * \< 60 years of age and amenorrheic for \>= 12 months prior to day 1 if uterus/ovaries are intact; or * \< 60 years of age, and the last menstrual period 6-12 months prior to day 1, if intact uterus/ovaries and meets biochemical criteria for menopause (follicle-stimulating hormone \[FSH\] and estradiol within institutional standard for postmenopausal status); or * \< 60 years of age, without a uterus, and meets biochemical criteria for menopause (FSH and estradiol within institutional standards for postmenopausal status); or * \< 60 years of age and history of bilateral oophorectomy; surgery must have been completed at least 4 weeks prior to day 1; or * Prior radiation castration with amenorrhea for at least 6 months * Patients must have estrogen and/or progesterone receptor positive histologically confirmed stage I-III adenocarcinoma of the breast * Patients must have completed recommended local therapy and adjuvant chemotherapy for breast cancer * Plan to treat with anastrozole for at least 12 months * Eastern Cooperative Oncology Group (ECOG) performance status between 0-2 * Patients must be disease-free of other prior invasive malignancies for ≥ 5 years with the exception of curatively-treated basal cell or squamous cell carcinoma of the skin or carcinoma in situ of the cervix. Prior early stage breast cancers are also allowed as long as prior treatment did not include aromatase inhibitors. * Patients must have worst pain rated as less than 4 out of 10 on the following question: "In the past week, how much pain have you had on a scale of 0 to 10, where 0 equals no pain and 10 means the worst pain you can imagine; " NOTE: This question regarding patient's pain should be completed within one week prior to registration; this pain item may be completed orally prior to consent up to 7 days prior to registration; it is not necessary to complete this pain item via the PROMIS website * Patients must have adequate hepatic, hematologic and renal functioning to be able to be administered anastrozole at the discretion of the treating physician Exclusion Criteria: * Prior AI therapy with exemestane, letrozole, or anastrozole as adjuvant therapy or for prevention of breast cancer; prior tamoxifen as adjuvant therapy or for prevention is allowed * Patients must not be currently taking (or have taken in the past 6 months) ongoing, daily analgesic medication for active, chronic conditions (i.e., rheumatoid arthritis, carpal tunnel syndrome, tenosynovitis, systemic lupus erythematosus, gout, fibromyalgia, or severe osteoarthritis involving the hands, wrists, hips, knees, feet or ankles); (note: patients taking daily low dose aspirin are allowed to participate in this trial) * Prior history of deep vein thrombosis (DVT) or pulmonary embolism in the past 5 years