Prasterone (Dehydroepiandrosterone) in Treating Postmenopausal Cancer Survivors With Vaginal Symptoms

Inclusion Criteria: 1. Age ≥ 18 years 2. Postmenopausal women with a history of breast or gynecologic cancer (currently no evidence of disease). Note: Postmenopausal status will be determined by the following criteria: 1. 12 months without a period or bilateral oophorectomy or complete chemical ovarian suppression for the past 12 months with continued suppression planned throughout the course of the study 2. menopausal status will be determined by an FSH and an estradiol value in the postmenopausal range (generally FSH \> 40IU/L and estradiol \< 10 pg/ml, depending on laboratory) if: * 9 months without a period or * post hysterectomy with at least one ovary remaining and less than 55 years old. Note: if age 55 or older with these criteria, then menopausal status does not need to be determined by labs 3. Significant vaginal complaints. Note: Defined as persistent vaginal dryness and/or pain with intercourse (dyspareunia) of sufficient severity to make a patient desire therapeutic intervention. 4. Eligibility questionnaire response must be moderate or worse levels of severity on one of the two symptoms, either dryness or dyspareunia. The protocol contains more information. 5. Vaginal symptoms must have been present ≥ 2 months prior to randomization. 6. Life expectancy \> 12 months. 7. Ability to complete questionnaires by themselves or with assistance. 8. Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) 0 or 1. 9. The patient must provide informed written consent. 10. Willing to return to the enrolling institution for follow-up. 11. Willing to provide blood samples for correlative research purposes. Exclusion Criteria: 1. Initiation or discontinuation of tamoxifen or aromatase inhibitors ≤ 2 months prior to randomization or plans to initiate or discontinue any of these medications during the 12-week study. 2. Current diagnosis of an active vaginal infection, if symptoms of vaginal infection, this must be ruled out (ie, foul discharge, fever). 3. Concurrent chemotherapy (long term adjuvant herceptin, lapatanib, and/or bevacizumab is allowed. 4. Planned use of any vaginal preparations during the study period (including any over the counter or herbal preparations). Note: Water-based lubricants (such as KY jelly) are allowed during sexual intercourse. 5. Use of any daily non-hormonal vaginal preparations ≤ 1 week prior to study entry. Exception: Daily water-based lubricants for sexual intercourse. Note: Patients who stop agent may be enrolled after one week. 6. Current (≤ 4 weeks prior to randomization), or planned during the study period, use of any estrogen product or any kind of hormonal vaginal product including bioidentical hormones, estriol or any androgen product. 7. Use of pharmacologic soy or phytoestrogen preparations (Dietary intake of soy - ie milk is acceptable). 8. On a placebo controlled trial for endocrine therapy. 9. Prior or concurrent pelvic radiation therapy. 10. Prior radical pelvic surgery, specifically vaginectomy or pelvic exenteration (TAH/BSO) is allowed). 11. Diagnosis of any of the following conditions within the past five years: 1. Essential vulvodynia 2. Vulvar vestibulitis 3. Bartholin cyst/abscess 4. History of Bartholin gland surgery 5. Lichen sclerosis 6. Lichen planus of the vulvovaginal region 7. Desquamative vaginitis 12. History or current diagnosis of any of the following conditions: 1. Vulvar or vaginal dysplasia 2. Vaginal prolapse 13. Women of childbearing potential, premenopausal women.