Cancer can spread from where it started (the primary site) to other parts of the body.
When cancer cells break away from a tumor, they can travel to other areas through either the bloodstream or the lymph system. If they travel through the lymph system, the cancer cells may end up in lymph nodes. Most of the escaped cancer cells die or are killed before they can start growing somewhere else. But one or two might settle in a new area, begin to grow, and form new tumors. This spread of cancer to a new part of the body is called metastasis.
White blood cells, such as B cells and T cells, attack any bacteria or viruses they find in the lymph. When cancer cells break away from a tumour, they may become stuck in one or more of the nearest lymph nodes.
