Understanding bone
Bone is a living tissue. The hard bone tissue is made of collagen fibres (tough, elastic fibres) and minerals (gritty, hard material). There are two main types of cells within the hard bone tissue that make and mould bone. One type (osteoblasts) makes and lays down bone material. Another type (osteoclasts) resorbs (dissolves) particles of bone. These cells are active throughout life. They work in a balanced way to make and mould bone, repair damage and keep the bone structure correctly 'woven'. There is a slow but constant turnover of bone. Chondrocytes are cells which make cartilage, the tissue that covers the ends of bones in joints.
In the centre of some larger bones is the soft bone marrow. This is where blood cells are made (red blood cells, white blood cells, and platelets).
What is cancer?
Cancer is a disease of the cells in the body. The body is made up from millions of tiny cells. There are many different types of cell in the body, and there are many different types of cancer which arise from different types of cell. What all types of cancer have in common is that the cancer cells are abnormal and multiply 'out of control'.
A malignant tumour is a 'lump' or 'growth' of tissue made up from cancer cells which continue to multiply. As they grow, malignant tumours invade into nearby tissues and organs which can cause damage.
Malignant tumours may also spread to other parts of the body. This happens if some cells break off from the first (primary) tumour and are carried in the bloodstream or lymph channels to other parts of the body. These small groups of cells may then multiply to form 'secondary' tumours (metastases) in one or more parts of the body. These secondary tumours may then grow, invade and damage nearby tissues, and spread again.
Some cancers are more serious than others, some are more easily treated than others (particularly if diagnosed at an early stage), some have a better outlook (prognosis) than others.
So, cancer is not just one condition. In each case it is important to know exactly what type of cancer has developed, how large it has become, and whether it has spread. This will enable you to get reliable information on treatment options and outlook. See separate leaflet called 'What are Cancer and Tumours' for further details about cancer in general.
What is primary bone cancer?
Cancer of the bone can be divided into primary bone cancer and secondary bone cancer.
Types of primary bone cancer
There are different types of primary bone cancer. They are classified by the type of cell which occurs in the cancer. Most types of primary bone cancer end with ...sarcoma. A sarcoma is a cancer that originates from cells which occur in and make connective tissues (supporting tissues) of the body. For example, bone, muscle, cartilage, ligaments, etc.
Osteosarcoma
This is the most common type of primary bone cancer, but even this is rare. It arises from bone forming cells. Most cases occur in young people between the ages of 10 to 25, but it can occur at any age. It typically develops in the growing ends of the bone in young people, most commonly in bones next to the knee. However, any bone can be affected.
Ewing's sarcoma
This is named after the doctor who first described it in the 1920's. The cells of this cancer look different to the more common osteosarcoma. Most cases occur in young people between the ages of 10 to 20, but it can occur at any age. It most commonly affects the pelvis and long bones of the leg. However, any bone can be affected.
Chondrosarcoma
This type of cancer arises from cartilage forming cells. As well as occuring in the cartilage, a chondrosarcoma may also develop within a bone, or on the surface of a bone. Most cases occur in people between the ages of 40 and 75. It most commonly affects the pelvis, scapula (shoulder blade), ribs, and the bones of the upper parts of the arms and legs.
Other
Other rare types of primary bone tumour include fibrosarcoma, leiomyosarcoma, malignant fibrous histiocytoma, and chordoma.
