A RANDOMIZED, DOUBLE-BLIND, PARALLEL-GROUP, MULTICENTRE, PHASE III STUDY TO COMPARE THE EFFICACY AND TOLERABILITY OF FULVESTRANT (FASLODEX TM) 500 MG WITH ANASTROZOLE (ARIMIDEX TM) 1 MG AS HORMONAL TREATMENT FOR POSTMENOPAUSAL WOMEN WITH HORMONE RECEPTOR-POSITIVE LOCALLY ADVANCED OR METASTATIC BREAST CANCER WHO HAVE NOT PREVIOUSLY BEEN TREATED WITH ANY HORMONAL THERAPY (FALCON)

INTERVENTION: PATIENTS WILL BE ASSESSED FOR ELIGIBILITY FOR THE STUDY BASED ON LOCAL LABORATORY RESULTS FOR HORMONE RECEPTOR STATUS. APPROXIMATELY 450 WOMEN WILL BE RANDOMISED 1:1 (FULVESTRANT: ANASTROZOLE). PATIENTS WILL BE STRATIFIED AT RANDOMISATION BASED ON WHETHER (1) THEY HAVE LOCALLY ADVANCED OR METASTATIC BREAST CANCER (2) THEY HAVE RECEIVED PRIOR CHEMOTHERAPY FOR LOCALLY ADVANCED OR METASTATIC BREAST CANCER OR NOT AND (3) THEY HAVE MEASURABLE OR NON‐MEASURABLE DISEASE. TO MAINTAIN BLINDING, PATIENTS RANDOMISED TO FULVESTRANT WILL ALSO RECEIVE PLACEBO TABLETS TO MATCH ANASTROZOLE AND PATIENTS RANDOMISED TO ANASTROZOLE WILL ALSO RECEIVE PLACEBO INJECTIONS TO MATCH FULVESTRANT. PATIENTS WILL START STUDY TREATMENT ON THE DAY OF RANDOMISATION (DAY 0 [VISIT 2]). STUDY VISITS WILL OCCUR AT SCREENING (DAY ‐28 TO ‐1), RANDOMISATION (DAY 0), DAY 14, WEEKS 4, 8, 12, 16, 20, 24 AND EVERY 12 WEEKS THEREAFTER (TABLE 1) UNTIL PROGRESSION. UP TO THE DATA CUT‐OFF FOR THE PRIMARY ANALYSIS, ALL RANDOMISED PATIENTS WILL BE ASSESSED BY COMPUTED TOMOGRAPHY (CT) OR MAGNETIC RESONANCE IMAGING (MRI) EVERY 12 WEEKS RELATIVE TO THE DATE OF RANDOMISATION, UNTIL DOCUMENTED EVIDENCE OF OBJECTIVE DISEASE PROGRESSION (REGARDLESS OF WHETHER ON STUDY TREATMENT OR NOT). PATIENTS WITH EVIDENCE OF METASTATIC BONE LESIONS AT BASELINE MUST ALSO HAVE A BONE SCAN/SKELETAL X‐RAY SURVEY EVERY 12 WEEKS. CONDITION: PRIMARY OUTCOME: Compare the progression free survival (PFS) in patients treated with Fulvestrant with those treated with Anastrozole; NAME OF THE RESULT: Compare the progression free survival in patients treated with Fulvestrant with those treated with Anastrozole.; USED MEASURING METHOD :Stratified log‐rank test; PERIOD OF TIME WHERE THE MEASUREMENT WILL BE CONDUCTED AND WHICH WILL ALLOW OBTAINING THE PRIMARY RESULT: Baseline RECIST 1.1 assessments and then every 12 weeks until the earliest of disease progression evident, patient dies or has surgery/radiotherapy for their disease. SECONDARY OUTCOME: Compare the Overall Survival (OS, death due to any cause) in patients treated with Fulvestrant with those treated with Anastrozole when 50% of patients are recorded as having died. ; NAME OF THE RESULT: Compare the Overall Survival (death due to any cause) in patients treated with Fulvestrant with those treated with Anastrozole when 50% of patients are recorded as having died. ; USED MEASURING METHOD :Stratified log‐rank test ; PERIOD OF TIME WHERE THE MEASUREMENT WILL BE CONDUCTED AND WHICH WILL ALLOW OBTAINING THE SECONDARY RESULT: Following disease progression, patients will be contacted at 12 weekly intervals to determine survival status INCLUSION CRITERIA: 1. PROVISION OF SIGNED, WRITTEN INFORMED CONSENT PRIOR TO ANY STUDY SPECIFIC PROCEDURES. 2. HISTOLOGICAL CONFIRMATION OF BREAST CANCER. 3. POSITIVE HORMONE RECEPTOR STATUS (ER +VE AND/OR PGR +VE) OF PRIMARY OR METASTATIC TUMOUR TISSUE BASED ON LOCAL LABORATORY ASSESSMENT. 4. HAVE EITHER . LOCALLY ADVANCED DISEASE NOT AMENABLE TO SURGERY OR RADIOTHERAPY OF CURATIVE INTENT. PATIENTS MAY HAVE HAD ONE LINE OF CYTOTOXIC CHEMOTHERAPY, FOLLOWING WHICH THEY MUST REMAIN UNSUITABLE FOR THERAPY OF CURATIVE INTENT. OR . METASTATIC DISEASE PATIENTS MAY HAVE RECEIVED ONE LINE OF CYTOTOXIC CHEMOTHERAPY AS PREVIOUS TREATMENT OF BREAST CANCER BUT MUST SHOW PROGRESSIVE DISEASE PRIOR TO ENROLMENT. 5. AT LEAST 1 LESION (MEASURABLE AND/OR NON‐MEASURABLE) THAT CAN BE ACCURATELY ASSESSED AT BASELINE AND IS SUITABLE FOR REPEATED ASSESSMENT BY CT, MRI OR PLAIN X‐RAY. 6. POSTMENOPAUSAL WOMAN, DEFINED AS A WOMAN FULFILLING ANY 1 OF THE FOLLOWING CRITER