Preoperative Estetrol in Breast Cancer

The study is designed as a single-center, randomized, double-blind, placebo-controlled study in pre- and postmenopausal women who will undergo surgery for breast cancer. Subjects will either receive estetrol or placebo during a 2 week treatment period. Several biological markers, such as a cellular growth marker and cell death markers, will be assessed in the tumor tissue and surrounding normal tissue before and after the treatment period. In addition, receptor studies will be performed. During the 2 week interval between diagnosis of breast cancer and surgical resection, no therapy for breast cancer is usually administered.