The main categories of cancer include:
- Carcinoma : cancer that begins in the skin or in tissues that line or cover internal organs. There are a number of subtypes of carcinoma, including adenocarcinoma, basal cell carcinoma, squamous cell carcinoma, and transitional cell carcinoma.
- Sarcoma : cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.
- Leukaemia : cancer that starts in blood-forming tissue such as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter the blood.
- Lymphoma and myeloma : cancers that begin in the cells of the immune system.
- Central nervous system cancers : cancers that begin in the tissues of the brain and spinal cord.
Not all tumours are cancerous; tumours can be benign or malignant.
Benign tumours aren’t cancerous. They can often be removed, and, in most cases, they do not come back. Cells in benign tumours do not spread to other parts of the body.
Malignant tumours are cancerous. Cells in these tumours can invade nearby tissues and spread to other parts of the body through the bloodstream or lymphatic system. The spread of cancer from one part of the body to another is called metastasis.
Some cancers do not form tumours. For example, leukaemia is a cancer of the bone marrow and blood.
The lymphatic system is part of the immune system – the body’s natural defence against infection and disease. It’s made up of organs such as bone marrow, the thymus, the spleen and lymph nodes. The lymph nodes throughout the body are connected by a network of tiny lymphatic tubes (ducts). The lymphatic system has two main roles: it helps to protect the body from infection and it drains fluid from the tissues.