Letrozole in Uterine Leiomyosarcoma

Inclusion Criteria:

1. Patient or a legally authorized representative must have signed an approved informedconsent and authorization permitting the release of personal health information.

2. Patient must have histologically confirmed newly diagnosed uterine leiomyosarcomawith disease limited to the uterus (FIGO 2009 Stage I). Submission of pathologyreport documenting uterine leiomyosarcoma histology is required in the IRT SourceDocument Portal following randomization.

3. Patient tumors must express ER positivity by immunohistochemistry (ER expressiongreater than 10% by immunohistochemistry). ER status test results must be providedat enrollment. Sites are required to report results of ER status testing in the IRTSource Document Portal.

4. Patient must have completed hysterectomy and bilateral salpingo-oopherectomy no morethan 12 weeks from enrollment.

5. All patients must have NO measurable disease as defined by RECIST 1.1 within 6 weeksof enrollment. Measurable disease is defined as at least one lesion that can beaccurately 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 orcaliper measurement by clinical exam; or greater than or equal to 20 mm whenmeasured by chest x-ray. Lymph nodes must be greater than or equal to 15 mm in shortaxis 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/laboratorylower 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 erythrocytetransfusions to achieve this hemoglobin level at the discretion of theInvestigator. Initial treatment must not begin earlier than the day aftererythrocyte transfusion). Renal function:

• Serum creatinine less than or equal to 1.5 x ULN Hepatic function:

• AST (aspartate aminotransferase) and ALT (alanine aminotransferase) less thanor 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.

Exclusion Criteria:

Exclusion Criteria 1. Patients who do not have pure uterine sarcomas (i.e., no mixed malignant mullerian tumors are permitted).

2. Patients with any other severe concurrent disease, which would make the patientinappropriate for entry into this study, including significant hepatic, renal, orgastrointestinal diseases.

3. Patients with concomitant invasive malignancy or a history of prior malignancyexcept non-melanoma skin cancer, in situ cervical cancer, or other cancer for whichthe patient has been disease-free for at least three years. Patients are alsoexcluded if their previous cancer treatment contraindicates this protocol.

4. Patients who have a history of taking any aromatase inhibitor within the past 5years.

5. Patients with active or uncontrolled systemic infection. 6. Patients with history ofuncontrolled cardiac disease, i.e., uncontrolled hypertension (defined as systolicgreater than 150 mm Hg or diastolic greater than 90 mm HR despite antihypertensivemedications), unstable angina, recent myocardial infarction (within prior 6 months),uncontrolled congestive heart failure (NYHA Class II or greater), clinicallysignificant cardiac arrhythmias, and cardiomyopathy with an ejection fraction under 40%.

6. Patients currently receiving chemotherapy or radiation therapy. 8. Patients withsevere hepatic impairment and/or cirrhosis. 9. Patients with duodenal stent or otherGI disorder/defect that would interfere with absorption of oral medication.

7. Patients deemed otherwise clinically unfit for clinical trial per investigatorsdiscretion.

8. Patients with known hypersensitivity to any of the excipients of letrozole. 12.Patients who are pregnant or breast-feeding. 13. Patients who are currently part ofor have participated in any clinical investigation with an investigational drugwithin 30 days of prior to enrollment.

9. Patients currently using systemic estrogens, including herbals and supplements withestrogenic properties. The use of vaginal estrogen is permitted if symptoms arerefractory to moisturizers and lubricants.