How Cancer Cells Grow and Spread The place where cancer starts to grow is called the primary site. Although some cancers may spread to more than one area of the body to form multiple secondaries or metastases. In order to spread, some cells from the primary cancer must break away, travel to another part of the body and start growing there. Cancer cells don't stick together …show more content…
If the cancer cells go into small blood vessels they can then get into the bloodstream. They are called circulating tumour cells. Researchers are currently looking at using blood tests to find circulating tumour cells to diagnose cancer and avoid the need for tests such as biopsies. They are also looking at whether they can test circulating cancer cells to predict which treatments will work best for each patient. The circulating blood sweeps the cancer cells along until they get stuck somewhere. Usually they get stuck in a very small blood vessel called a capillary. Out of many thousands of cancer cells that reach the blood circulation only a few will survive to form a secondary cancer or metastasis. Some cancer cells are probably killed off by the white blood cells in our immune system. Others cancer cells may die because they are battered around by the fast flowing blood. Cancer cells in the circulation may try to stick to platelets to form clumps to give themselves some protection. Platelets are blood cells that help the blood to clot. This may also help the cancer cells to be filtered out in the next capillary network they come across so they can then move into the surrounding tissues (“How do Cancer Cells Grow and Spread?”,