What is bone cancer?

Primary bone cancer starts in the cells of the bones. This is different from secondary or metastatic bone cancer, which spreads to the bones from elsewhere in the body.

If you have secondary bone cancer, this is not the right section for you. You need to look at the section for your type of primary cancer which is named after the part of your body where your cancer started.

The bones

The skeleton

There are more than 200 bones in the human body. Together they form the skeleton. The bones:

  • support the body
  • protect parts of the body
  • act as levers for the muscles so we can stand and move

The long bones of the arms and legs are supporting bones. The bones of the rib cage protect the organs of the chest. The skull bones protect the brain.

Diagram of the skeleton

The end of every long bone is covered with a smooth tissue called cartilage. Tendons hold the long bones together where they join.

Together, cartilage and tendons form joints that allow the bones to move smoothly against each other.

The bone cells

Bone is a framework of soft supporting tissue called connective tissue. It also contains minerals such as calcium which hardens the bones. This framework gives the bone its strength. Throughout this framework are the bone cells. 

There are 3 main types of cells in our bones which work together to maintain the shape, strength and health of the bones:

  • osteoblasts
  • osteoclasts
  • osteocytes

If a bone gets damaged, the osteoblasts make new bone to repair the damage.

The osteoclasts break down any extra bone framework that the osteoblasts make and reshape the bone.

When bone forms, osteoblasts are trapped within it and become part of the framework. They are then called osteocytes and maintain the bone structure.

Diagram of an osteocyte a type of bone cell

Inside some of the bones of the body is a space that is filled with bone marrow. Blood cells are made in the bone marrow. All blood cells develop from stem cells which are found in the bone marrow.

Diagram of bone marrow

Where does bone cancer start?

Primary bone cancer starts in cells of the bones. Doctors sometimes use the term bone sarcoma when they talk about primary bone cancer. Sarcomas are cancers that start in any connective tissue in the body. This includes the bones but also:

  • muscles
  • tendons
  • blood vessels
  • fatty tissues

There are several different types of primary bone cancer. The most common types are:

  • osteosarcoma - is more common in the upper arms or legs (usually around the knee)
  • chondrosarcoma - is mostly found in the bones of the pelvis, including those that make up the hip joints, shoulder bones, thigh bones or ribs
  • Ewing sarcoma - often starts in the pelvis, thigh bones, shoulder bones or the ribs

Other rarer types include:

  • spindle cell sarcoma - is more common in the bones of the legs
  • chordoma - most commonly starts in the bone at the bottom of the spine (sacrum), the bones (vertebrae) of the back (spine), or the bones of the face and the skull

Myeloma

A type of cancer called myeloma can affect the bones. People sometimes call it bone cancer. It develops from cells in the bone marrow called plasma cells. But it is not a type of primary bone cancer because it does not start in the bone itself. So if you have myeloma, your treatment will be different.

Where does bone cancer spread?

When a primary bone cancer starts to grow, the cancer cells multiply and begin to break down the bone. This weakens the bone in that area.

Bone cancer cells can break away from the primary bone tumour and travel to other organs, usually the lungs or other bones. There they can grow into secondary tumours.

Who gets bone cancer?

Bone sarcoma is linked to age. Osteosarcoma is more common in adolescents (10 to 19 years), chondrosarcoma in adults, and Ewing sarcoma in children (0 to 14 years) as well as adolescents.

How common is bone cancer?

Bone cancer is very rare. Around 550 people are diagnosed each year in the UK. That’s more than 1 case diagnosed every day.