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

RATIONALE: Magnesium oxide may help relieve hot flashes symptoms in women with a history of breast cancer.

PURPOSE: This randomized clinical trial studies how well a high-dose or a low-dose of magnesium oxide works compared to placebo in treating menopausal women with hot flashes and a history of breast cancer.

OBJECTIVES:

Primary

* Evaluate the efficacy of magnesium oxide on hot flashes in women with a history of breast cancer.

Secondary

* Evaluate the side-effect profile of magnesium oxide in this study population.
* Evaluate the effect of magnesium oxide on the secondary outcomes hot flash frequencies, hot flash severities, toxicities (including diarrhea), and hot flash-related daily interference on activities.
* Evaluate the effect of magnesium oxide on the change of magnesium level (for the first 150 patients).

OUTLINE: This is a multicenter study. Patients are stratified according to age (18-49 years vs ≥ 50 years), current tamoxifen and/or selective estrogen receptor modulator (yes vs no), current aromatase inhibitor (yes vs no), and daily frequency of hot flashes (4-9 vs ≥ 10). Patients are randomized to 1 of 4 treatment arms.

* Arm I: Patients receive a low-dose of magnesium oxide orally (PO) daily (QD).
* Arm II: Patients receive a high-dose of magnesium oxide PO QD.
* Arm III: Patients receive a low-dose of placebo PO QD.
* Arm IV: Patients receive a high-dose of placebo PO QD. In all arms, treatment continues for 8 weeks in the absence of unacceptable toxicity.

Some patients may continue or crossover to receive magnesium for 4 more weeks.

Patients complete the Hot Flash Diary daily for 9 weeks beginning 1 week before treatment. They also complete the Symptom Experience Questionnaire, the Profile of Mood States (POMS), and Hot Flash-Related Daily Interference Scale (HFRDIS) questionnaires periodically during study treatment.

Patients undergo blood sample collection at baseline and at the end of weeks 5 and 9 for serum magnesium level analysis.

Eligibility Criteria:
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)