What is breast cancer?
Breast cancer is a malignant tumour that starts in the breast tissue. The majority of breast cancers begin in the milk ducts (ductal cancers). A small number start in the milk sacs or lobules (lobular cancers). Within these two groups there are different subtypes of breast cancer. Some grow very slowly. Others develop more rapidly.
Breast cancer can spread to the lymph glands and to other parts of the body, such as the bones and liver.