Magnesium Oxide in Treating Postmenopausal 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.

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)