Changing paradigms in breast cancer treatment

In only the past century, the landscape of breast cancer treatment has completely changed. The Halstedian hypothesis of the "contiguous spread" of breast cancer has been replaced by a consideration of its systemic nature. Today, patients with early-stage breast cancer are managed with breast-conserving therapy, which is as effective as mastectomy. Sentinel lymph node biopsy has largely replaced axillary lymph node dissection. Post-operative radiotherapy, chemotherapy and endocrine therapy have increased survival. Pre-operative cytotoxic therapy allows for less extensive surgery and for a curative resection even in more advanced stages. Rapid progress in molecular oncology revealed a large heterogeneity of breast cancer, resulting in a more personalized approach. Targeted therapies directed against epidermal growth factor receptor type 2 (HER2) have improved survival in HER2-positive breast cancer, which was once a poor-prognosis entity. Multi-gene prognostic signatures better predict prognosis and allow many patients to avoid chemotherapy. Personalized treatment has resulted in decreased toxicity and an improved quality of life. Within the past decades, breast cancer has become a good-prognosis malignancy with a five-year survival in the range of 80-85%. Future development of personalized medicine may further refine treatment based on the tumor's molecular features.