Soy Protein Supplement In Treating Hot Flashes in Postmenopausal Women Receiving Tamoxifen for Breast Disease

Eligibility Criteria: 1. Histologic documentation of atypical ductal hyperplasia, ductal carcinoma in situ (DCIS), lobular carcinoma in situ (LCIS), or invasive adenocarcinoma of the breast stages I-III A. 2. Current daily tamoxifen use. Any planned surgery, adjuvant chemotherapy or radiation must have been completed. 3. History of bothersome hot flushes: ≥ 7 hot flushes/day, sufficiently severe that intervention is desired. Participants must have had bothersome hot flushes for at least one month prior to enrollment. 4. Postmenopausal status: surgical menopause, no menses for ≥ 1 year or postmenopausal FSH levels. 5. No concurrent use of vitamin E, progestins (Megace® or others), clonidine, belladonna derivative or commercially available soy supplement preparations for treatment of hot flushes. Participants must have at least a 4-week washout period prior to day 1 of run-in if any of these have been used. Participants may be taking low doses of vitamin E that are part of a multivitamin. 6. Concurrent use of anti-depressant, such as Paxil® , Prozac®, or Effexor® is allowed if the participant has been on a stable dose for more than a month and the purpose of the medication is for other than control of hot flushes. If SSRI's are used for hot flashes, they must be discontinued for 4 weeks prior to day 1 of run-in. 7. No concurrent systemic hormone replacement therapy or use of vaginal estrogen creams. Use of the estradiol releasing vaginal ring (Estring®) is allowed. 8. No h…