Phase III Randomized Study of Luteal Phase vs. Follicular Phase Surgical Oophorectomy and Tamoxifen in Premenopausal Women With Metastatic Hormone Receptor-Positive Breast Cancer

Rationale: Previous research suggests that women who have their ovaries removed as part of their treatment for breast cancer may live longer if the ovarian surgery is performed during the luteal phase (last 14 days of the menstrual cycle) rather than the follicular phase (the first 14 days of the menstrual cycle). The current study will evaluate this important research question in premenopausal women with metastatic hormone receptor-positive breast cancer who will be treated with surgery and tamoxifen.

Purpose: The purpose of this research is to find out if premenopausal women with breast cancer that has spread to other parts of the body live longer if their ovaries are removed during the second half of the menstrual cycle. This study will compare how long women live if they have their ovaries removed during the first half of their menstrual cycle (follicular phase) to how long women live if they have their ovaries removed during the second half of their menstrual cycle (luteal phase). Tamoxifen will also be given to study participants.

Treatment: Study participants will have tests performed in advance of surgery to remove their ovaries. Surgery will be performed within four weeks of these tests. The exact day will be determined by the study participant's menstrual history and by a process called randomization, which is a random decision making process to determine if each study participant will have their surgery during the first or second half of their menstrual cycle. On the day of surgery, blood will be taken immediately prior to surgery and three hours after surgery for hormone tests. After the surgery, study participants will be given tamoxifen in oral pills for daily consumption. Study participants will be asked to return to the hospital every two months for tests and distribution of additional tamoxifen tablets. Treatments will be discontinued for disease progression or unacceptable adverse effects.