Letrozole in the Treatment of Advanced or Recurrent Hormone Receptor Positive Endometrial Cancer

Inclusion Criteria: * Signed informed consent * Age \> 18 years * Presence of histologically proven adenocarcinoma or adenosquamous carcinoma of the endometrium * Presence of advanced or recurrent endometrial cancer, FIGO stage I-IV, incurable with surgery and/or radiation therapy * Documented ER and/or PgR positive endometrial cancer. Hormone receptor positivity is defined according to routine practice at each participating laboratory. * Patient must be postmenopausal defined as * Age ≥55 years. * Age \<55 but no spontaneous menses for at least 1 year. * Age \<55 and spontaneous menses within the past 1 year, but currently amenorrheic (e.g., spontaneous or secondary to hysterectomy), and with postmenopausal gonadotrophin levels (luteinizing hormone and follicle stimulating hormone levels \>40 IU/L) or postmenopausal estradiol levels (\<5 ng/dL) or according to the definition of "postmenopausal range" for the laboratory involved. * Bilateral oophorectomy * Radiation menopause * Presence of measurable disease (by clinical/radiological examination - according to RECIST criteria : minimum indicator lesion size : 20 mm (unless spiral CT scan in which case \> 10 mm) * ECOG performance status of 0, 1 or 2 * Adequate bone marrow function (WBC ≥ 3.5 x 1'000'000'000/L and platelets ≥ 100.0 x 1'000'000'000/L) and hemoglobin \> 10.0 g/dl * Adequate renal function (creatinine \< 120 µmol/L) and hepatic function (bilirubin \< 25 µmol/L, AST (SGOT \< 60 U/L) * Minimum life expectancy of at least 6 months * Patients who are accessible for treatment and follow-up Exclusion Criteria: * Presence of non-measurable disease only * Other concomitant anti-cancer treatment (except external radiation treatment \[XRT\] for symptomatic metastatic lesions if other assessable untreated lesions are present) * Prior treatment with aromatase inhibitors or anti-estrogens (up to one previous progestational hormone therapy regimen for recurrent disease is permitted) * Clear cell or papillary serous histology, uterine sarcomas, mixed Mullerian tumors (MMT) and/or adenosarcomas * Other concurrent malignant disease with the exception of cone-biopsied in situ carcinoma of the cervix uteri, or adequately treated basal or squamous cell carcinoma of the skin, or other curable cancers e.g. Hodgkin's disease or non-Hodgkin lymphoma (NHL), provided 5 years have elapsed from completion of therapy, and there has been no recurrence * Known central nervous system (CNS) metastases, bilateral diffuse lymphangiosis carcinoma of the lung (\>50 % of lung involvement, or dyspnea at rest requiring supplemental oxygen therapy), evidence of metastases estimated as more than a third of the liver as defined by sonogram and/or CT scan * Uncontrolled endocrine disorders such as diabetes mellitus, confirmed hypo- or hyperthyroidism, Cushing's Syndrome, Addison's disease (treated or untreated) * Unstable angina and uncontrolled cardiac disease * Treatment with other investigational drugs (drugs not marketed for any indication) within the past 30 days and/or the concomitant use of investigational drugs * A history of non-compliance to medical regimens and patients who, in the opinion of the investigator, are unlikely to cooperate fully during the study * Inability to swallow pills Additional protocol-defined inclusion/exclusion criteria may apply.