1. Patient must have histologically confirmed uterine leiomyosarcoma with disease limited to the uterus (FIGO stage 1 or 2).
2. Tumors must express ER positivity by immunohistochemistry (ER expression greater than or equal to 10% by immunohistochemistry).
3. Must have completed hysterectomy and bilateral salpingo-oopherectomy no more than 12 weeks from initiation of therapy
4. All patients must have no measurable disease within 6 weeks of initiation of therapy. Measurable disease is defined by RECIST version 1.1.
5. Patient must be able to swallow oral medications.

1. Patients who have a history of taking any aromatase inhibitor.
2. Patients who do not have pure uterine sarcomas (i.e., no mixed malignant mullerian tumors).
3. Patients with active or uncontrolled systemic infection
4. Patients with concomitant invasive malignancy or a history of other invasive malignancies, with the exception of non-melanoma skin cancer, are excluded if there is any evidence of other malignancy being present within the past two years. Patients are also excluded if their previous cancer treatment contraindicates this protocol.
5. Patients who are pregnant or breast-feeding.

This is a randomized phase II study of letrozole (Femara) administered 2.5 mg orally daily to patients with newly diagnosed clinical stage I and II LMS. Using an adaptive randomization, patients will be assigned to either the treatment arm (letrozole group) or observation. The primary outcome for this trial is the time to progression.

Unfortunately, a stipend is not provided.

This is a clinical trial to test letrozole in patients with uterine leiomyosarcoma. The main question is will treatment with letrozole extend progression-free survival in patients. Patients will receive 2/5 mg of letrozole daily.