Techniques and Methodology Patients with primary breast cancer receiving neoadjuvant letrozole will undergo radiological assessment with digital mammogram, US including SWE, and MRI. Core biopsies will be taken at diagnosis and at surgery from tumour and peri-tumoural stroma, and assessed for biomarkers lysyl oxidase (LOX), fibronectin, collagen, proliferation, MCT4 and caveolin-1. All data will be correlated to peri-tumoural abnormalities on MRI and SWE.