Letrozole in Uterine Leiomyosarcoma

Inclusion criteria

1. Patient or a legally authorized representative must have signed an approved informed consent and authorization permitting the release of personal health information. 2. Patient must have histologically confirmed newly diagnosed uterine leiomyosarcoma with disease limited to the uterus (FIGO 2009 Stage I). Submission of pathology report documenting uterine leiomyosarcoma histology is required in the IRT Source Document Portal following randomization. 3. Patient tumors must express ER positivity by immunohistochemistry (ER expression greater than 10% by immunohistochemistry). ER status test results must be provided at enrollment. Sites are required to report results of ER status testing in the IRT Source Document Portal. 4. Patient must have completed hysterectomy and bilateral salpingo-oopherectomy no more than 12 weeks from enrollment. 5. All patients must have NO measurable disease as defined by RECIST 1.1 within 6 weeks of enrollment. Measurable disease is defined as at least one lesion that can be accurately measured in at least one dimension (longest diameter to be recorded). Each lesion must be greater than or equal to 10 mm when measured by CT, MRI or caliper measurement by clinical exam; or greater than or equal to 20 mm when measured by chest x-ray. Lymph nodes must be greater than or equal to 15 mm in short axis when measured by CT or MRI. 6. Patients must have an ECOG performance status of 0, 1, or 2. 7. Patients must have adequate organ and marrow function as defined below: NOTE: Institutional/laboratory upper limit of normal = ULN Institutional/laboratory lower limit of normal = LLN Bone marrow function: * Absolute neutrophil count (ANC) greater than or equal to 1500 cells/mcl * Platelet count greater than or equal to 100,000 cells/mcl * Hemoglobin greater than or equal to 9.0 g/dL (Patients may receive erythrocyte transfusions to achieve this hemoglobin level at the discretion of the Investigator. Initial treatment must not begin earlier than the day after erythrocyte transfusion). Renal function: • Serum creatinine less than or equal to 1.5 x ULN Hepatic function: * AST (aspartate aminotransferase) and ALT (alanine aminotransferase) less than or equal to 3.0 x ULN * Serum albumin greater than or equal to 2.5 g/dL 8. Patient must be at least 18 years of age. 9. Patient must be able to swallow oral medication.