Breast cancer is the most widespread cancer globally, with 7.8 million women alive at the end of 2020 diagnosed with the disease in the past five years. It can occur in women of any age after puberty, and its prevalence increases in later life. The cancer arises in the lining cells of ducts or lobules in the glandular breast tissue and can be invasive or non-invasive (in-situ). Initially, the cancerous growth is confined to the duct or lobule, where it generally has minimal potential for spread and causes no symptoms. However, over time, in-situ cancers may progress and invade the surrounding breast tissue, spreading to nearby lymph nodes or other organs in the body. Breast cancer in men is rare but can still occur, with most cases being invasive. Metastatic breast cancer is the primary cause of death in women diagnosed with the disease.
