Cancer can start in any organ or tissue in the body. A primary Cancer or tumour is the first, original tumour that develops in the body. Metastatic Cancer occurs when Cancer spreads from its original location (primary tumour) to a new part of the body. Metastatic tumours always start from Cancer cells in another part of the body. For example, Breast Cancer can spread from its primary site (the breast) to form a new tumour in a different part of the body, such as the bones. The Cancer cells in this second tumour are the same as the cells in the primary tumour – they are Breast Cancer cells, and not Bone Cancer cells. When this happens, it is called Metastatic Breast Cancer, and not Bone Cancer.
Every year in Canada, an average of 6,823 lung and bronchus, 2,494 colorectal, 815 female breast and 1,187 prostate cancers are diagnosed after they have metastasized (stage IV) (Canadian Cancer Statistics, 2018).
Metastatic Cancer may also be called:
- a secondary tumour or cancer
- metastasis (singular)
- metastases (plural)
Click here to view the metastatic breast cancer section.