Cancer can also be described according to the type of cell it started in. This can be just as important in how a cancer behaves and responds to treatment as the site where it started.
Our body is made up of millions of cells. The cells, organised together, make up all of our tissues and organs. There are different types of cells to carry out different functions in the body. Some types are very common and are found in almost all the organs in our body. Other types, such as the brain cells, are very specialised and only found in one part of our body.
The main types of cells in our body are:
- Epithelial cells These cover the outside of our body (as skin) and make up tissues that line the inside of our bodies and cover our organs.
- Cells of the blood and lymphatic system These are found in our blood, in the bone marrow (where blood cells are made) and in the lymphatic system (which fights infection).
- Connective tissue cells These cells are found in supportive and connective tissues in our body such as the muscles, bones and fatty tissue.
Cancers that start in each of these types of cells have different names.
Cancers that start in epithelial cells are called carcinomas. They are the most common type of cancer in adults and make up 80-90 out of every 100 (80-90%) cancers. Most lung, breast, prostate and bowel cancers are carcinomas.
There are different types of epithelial cells:
- Squamous cells are found in the skin and cover the surface of many parts of the body including the mouth, gullet (oesophagus) and the airways.
- Adeno cells form the lining of all the glands in the body including those in the breast, bowel, stomach, ovaries and prostate.
- Urothelial (transitional) cells line the bladder and parts of the urinary system.
- Basal cells are found in the skin.
Carcinomas may start in any of these types of cells.
- Squamous cell carcinomas start in squamous cells
- Adeno carcinomas start in the adeno cells
- Transitional cell carcinomas start in the urothelial cells
- Basal cell carcinomas start in the basal cells.
Leukaemias and lymphomas
Cancers that start in the blood or bone marrow (the tissues where white blood cells are formed to fight infection in the body) are called leukaemias.
Cancers that start in the lymphatic system (which helps the body fight infection) are called lymphomas.
Leukaemias and lymphomas are quite rare, making up fewer than 7 in 100 (7%) of cancers.
Cancers that start in connective tissue cells are called sarcomas.
Sarcomas are rare. They make up fewer than 1 in 100 (1%) of cancers.
Sarcomas are split into two main types:
- bone sarcomas, which are found in the bones
- soft tissue sarcomas, which develop in the other supportive tissues of the body.
Cancers that start in other types of cells
Cancer can develop in other types of cells but these cancers are rare. Brain tumours are the most common cancers in this group.