The QUEST study flow chart. ADH, atypical ductal hyperplasia; DCIS, ductal carcinoma in situ; ELD, extended latissimus dorsi; LCIS, lobular carcinoma in situ. *Prospective patients will undergo preoperative evaluation of the breast (mammogram/ultrasound scan/MRI and core biopsy) and axilla (ultrasound scan and fine-needle aspiration of suspicious nodes or preoperative sentinel lymph node biopsy) to determine whether they are likely to require postoperative radiotherapy (RT) according to each centre's local RT guidelines (for example, multifocality, grade 3, lymphovascular invasion and nodal involvement). **Delayed reconstructions must be performed within 12 months of randomisation. ***Patients in the delayed arm will complete baseline questionnaires prerandomisation and at 3 months and 6 months post mastectomy, then prereconstruction (usually approximately 12 months postoperative). Following reconstruction, follow-up will be as per the other arms – 3 months, 6 months, 12 months and annually for 5 years.