Letrozole in Patients With Ovarian Tumors

Primary Objectives: * To determine the objective response rate of Letrozole when administered to patients with advanced or recurrent borderline tumors or low-grade epithelial cancers from the ovary , fallopian tube or peritoneum. * To determine the time to tumor progression of patients with advanced or recurrent borderline tumors or low-grade epithelial cancers from the ovary, fallopian tube or peritoneum. * To identify the biological markers to predict response to Letrozole and study the aspects of the hormones in these types of tumors.