Surgery has always played a central role in the management of breast cancer, with local control via complete tumour resection long established as the cornerstone of effective breast cancer therapy. While extensive surgical resection in the form of the Halstead radical mastectomy dominated treatment up until at least the 1970s, the advent of adjuvant loco-regional and systemic therapies has resulted in a decrease in the magnitude of surgical intervention in recent decades. The Biomolecular or "-omics" era initiated with the discovery of the DNA double helix in 1953 and intensified by the completion of the human genome project in 2003 has seen an unprecedented expansion in our understanding of the molecular and genetic heterogeneity of cancer. This review will discuss how the clinical application of this knowledge in the direction of personalised risk assessment and breast cancer treatment has significant implications for modern surgical practice. (C) 2016 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.