Magnesium Oxide in Treating Postmenopausal Women With Hot Flashes and a History of Breast Cancer

DISEASE CHARACTERISTICS:

* Women with a history of breast cancer (currently without malignant disease)
* Bothersome hot flashes (defined by their occurrence ≥ 28 times per week and of sufficient severity to make the patient desire therapeutic intervention)
* Presence of hot flashes for ≥ 30 days prior to study registration
* Willingness to provide the biologic specimens as required by the protocol
* Hormone receptor status not specified

PATIENT CHARACTERISTICS:

* Women who are postmenopausal as defined by absence of a period in the past 12 months or bilateral oophorectomy

  * Women with at least one ovary but without a uterus should be deemed postmenopausal by either age over 55 or a combination of estrogen within a postmenopausal range (per local lab) and FSH over 40 mIU/mL
  * No women of childbearing potential or who are premenopausal
* Creatinine clearance \> 30 mL/min
* Ability to complete questionnaire(s) by themselves or with assistance
* ECOG performance status 0 or 1
* No history of allergic or other adverse reaction to magnesium
* No diabetes
* No patients with conditions that are implicated in decreased absorption of magnesium (e.g., Crohn disease, ETOH abuse)
* No patients who have diarrhea where magnesium might make it worse (per provider discretion)

PRIOR CONCURRENT THERAPY:

* None of the following current (≤ 28 days prior to registration) or planned therapies (tamoxifen, raloxifene, or aromatase inhibitors are allowed, but the patient must have been on a constant dose for ≥ 28 days and must not be expected to stop the medication during the study period):

  * Antineoplastic chemotherapy (trastuzumab or lapatinib are allowed)
  * Androgens
  * Estrogens (any delivery route)
  * Progestational agents
* No prior use of magnesium for hot flashes
* No current or planned use of gabapentin (for any reasons) or antidepressants (for any reasons) or other agents for treating hot flashes (except stable dose of vitamin E is allowed as long as it was started \> 30 days prior to study registration and are to be continued through the study period; soy is allowed, if it is planned to be continued at the same dose during the study period)
* No current use of magnesium for any indication (except one standard multiple vitamin dose is allowed per day)
* Not taking diuretics, corticosteroids, bile acid sequestrants, and other prescription and over-the-counter medications that may affect magnesium levels
* No current (≤ 7 days prior to registration) or planned use of other non-drug therapies for managing hot flashes, such as acupuncture or yoga (use of these therapies for other reasons is allowed)