What is breast cancer?
Breast cancer is defined as a cancerous tumour or growth that first develops on breast tissue. Breasts are primarily comprised of a fatty tissue which produces milk after pregnancy. This tissue extends up to the collarbone and from the armpit to the breastbone, therefore, different kinds of cancers materialize on different breast tissues. Breast cancer is a malignant tumour, which means, it can spread, or metastasize to other parts of the body.
Most often, breast cancer starts in cells that line the ducts, which are the tubes that carry milk from the glands to the nipple. This type of breast cancer is called ductal carcinoma. Cancer can also start in the cells of the lobules (the groups of glands that make milk) and is called lobular carcinoma. Both of these types of cancers can be in situ, which means the cancer is still in its original location and has not grown to surrounding tissues. The cancer can also be invasive, which means they have grown to surrounding tissues. To learn about less common types of breast cancer and to have an overview of all types of breast cancer, visit Breast Cancer Diagnosis in the Breast Cancer Treatment and Diagnosis section.
What is metastatic breast cancer?
Breast cancer is divided into five main stages, 0 through IV. The stages are based on the size of the tumour, the number of lymph nodes involved, and how much the cancer has spread. When breast cancer spreads beyond the area of the breast and into distant organs and tissues, the cancer is diagnosed at stage IV – this is known as metastatic breast cancer or advanced cancer.
Approximately, six to ten per cent of new breast cancer cases are initially diagnosed as Stage IV or metastatic and 20-30 per cent of those diagnosed with breast cancer will have it metastasize. The median survival after a metastatic breast cancer diagnosis is three years, up from 18 months in 1970 (Metastatic Breast Cancer Network).
Research on metastatic cancers in general is low – in fact, only five per cent of cancer research funds are spent on metastases while it kills 90 per cent of all cancer patients (Metastasis: a therapeutic target for cancer). In general, treatment choices are guided by breast cancer type, location and extent of metastasis in the body, previous treatments and other factors.
Today, there is an absence of definitive prognostic statistics and resources for those living with metastatic breast cancer. Every patient and their disease are unique – treatment for metastatic breast cancer is life-long and focuses on control of the disease and quality of life.