This guideline covers care and support for people with advanced (stage 4) breast cancer. It aims to help them and their healthcare professionals make shared decisions about tests and treatments to improve outcomes and quality of life. A table of NHS England interim treatment regimens gives possible alternative treatment options for use during the COVID-19 pandemic to reduce infection risk. This may affect decisions for patients with advanced breast cancer. See the COVID-19 rapid guideline: delivery of systemic anticancer treatments for more details. In August 2017, we reviewed the evidence for assessing oestrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) status on disease recurrence and changed the recommendations in section on diagnosis and management.