Study of Anastrozole +/- AZD8931 in Postmenopausal Women With Endocrine Therapy Naive Breast Cancer

Progression Free Survival as Evaluated by Response Evaluation Criteria In Solid Tumors (RECIST) 1.1

Time from the date of randomization until the date of objective disease progression (as per RECIST 1.1) or the date of death (by any cause in the absence of progression). Disease progression is defined using RECIST 1.1 as \>=20% increase in the sum of longest diameters of target lesions and an absolute increase of \>=5mm, taking as reference the smallest sum of longest diameters of target lesions since study start, or unequivocal progression in non-target lesions, or appearance of any new lesions.

Time frame: Tumour assessment by RECIST 1.1 every 12 weeks until data cut-off at 31 August 2012