Inclusion Criteria:

1. 18-years or older

2. Women with a prior breast cancer or who are at a high risk for developing the disease
and about to start tamoxifen therapy.

3. Participants must not be treated with concomitant chemotherapy or hormone therapy
other than tamoxifen. They must not have ovarian ablation or currently being treated
with radiation therapy and/or chronic corticosteroids.

4. The participant must not be taking anti-hot flash therapy (clonidine, bellergal,
megestrol acetate). Vitamin E, selective serotonin reuptake inhibitors, or herbal
remedies are allowed provided that the participant has been taking the remedy for at
least 4 weeks and intends to continue the remedy for at least the first month while
on the study, and allows for one-month follow up evaluation (hot flash diaries and
blood samples).

5. The participant must not be pregnant or lactating.

6. The participant is able and willing to sign an informed consent.