Inclusion Criteria

DISEASE CHARACTERISTICS:

- Meets 1 of the following criteria:

- History of breast cancer (currently without malignant disease)

- No history of breast cancer but wishes to avoid estrogen due to a perceived
increased risk of breast cancer

- Must have bothersome hot flashes (defined by their occurrence of ≥ 14 times per week
and of sufficient severity to make the patient desire therapeutic intervention) for ≥
1 month before study entry

- Has undergone treatment for cancer (patients other than breast cancer survivors are
eligible)

PATIENT CHARACTERISTICS:

- ECOG performance status 0-2

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- Creatinine clearance ≥ 30 mL/min

- No hypersensitivity to magnesium oxide

- No medical or other condition(s) that, in the opinion of the
investigator/sub-investigator, may compromise the objectives of the study

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- More than 4 weeks since prior and no concurrent antineoplastic chemotherapy,
androgens, estrogens, progestational agents, or gabapentin

- More than 28 days since prior and no other concurrent investigational drugs

- Concurrent tamoxifen, raloxifene, or aromatase inhibitors allowed provided patient
has been on a constant dose for > 4 weeks AND is not expected to stop the medication
during the study period