Bone cancer may be of two basic types:
Primary bone cancer - cancer that begins in the bone
Secondary bone cancer - cancer that begins elsewhere in the body (for example lungs, breast, liver etc.) that has spread to the bone
Primary bone cancer is a rare form of cancer - about 500 cases are diagnosed in the UK each year (only about one in every 500 cancers).
Around 2,600 people in United States of America are diagnosed with primary or secondary bone cancer each year. Bone cancers make for 2% of all cancers in the USA.
How does bone cancer begin?
The cancer usually begins with bone pain that usually gets worse over time and may wake the affected person from sleep. There may be bone fractures on relatively less severe impact or trauma and swelling and tenderness over the affected area as well.
Joint movement may be difficult if the joints are affected. In addition, there may be weakness, weight loss, fever and other general symptoms. 1-6
Causes and risk factors
The exact causes of bone cancer are unknown. Risk factors include exposure to radiation in the past, having Paget’s disease of the bone that affects the growth cycle of the bone cells.
Only around 1% of persons with Paget’s disease may develop bone cancer. There is no evidence that an injury to the bone causes cancer. There may be a link to rare genetic conditions such as Li-Fraumeni syndrome.
Types of Primary bone cancer
Bone is made up of cells that grow and collagen fibres (tough, elastic fibres) as well as minerals like Calcium that give it the hardness. There are two main types of cells within the hard bone tissue that mould the bone. These cells are Osteoblasts and Osteoclasts.
Osteoblasts form the bone by laying down bone material. Osteoclasts dissolve the particles of bone and cause resorption. These cells are active throughout life and work in tandem balance to keep the bone constantly growing and dissolving. There is a slow but constant turnover of bone.
Another type of cell is chondrocytes which make cartilage. These make the hard tissues that cover the ends of bones in joints. In the centre of some larger bones is the soft bone marrow that is the place where blood cells are manufactured.
Although bone cancers are rare, there are four major types of bone cancer of primary origin. These include osteosarcoma, Ewing’s sarcoma, spindle cell sarcoma and chondrosarcoma.
This is the commonest type of primary bone cancer. In the United Kingdom, around 150 new cases are diagnosed each year.
The cancer is seen commonly in children and young adults between ages of 5 and 20. Among young people osteosarcoma is the third most common cancer after leukaemia and brain tumours.
Osteosarcoma affects larger bones, such as the thigh bone (femur) or the shin bone (tibia).
Around 100 new cases of this cancer are detected in the UK each year. Ewing’s sarcoma also affects children and young people aged between 10 and 20.
Ewing’s sarcoma also affects larger bones like pelvis, thigh bone or shin bone.
Spindle cell sarcoma
Around 80 new cases of this cancer are diagnosed in UK each year. This cancer is similar to osteosarcoma and is diagnosed in adults aged 40 or over.
This cancer is diagnosed in 80 individuals in UK each year. This is the cancer of middle ages and is diagnosed in people aged between 40 and 50.
Commonly affected sites include pelvis, thigh bone, upper arm bone, shoulder blade (scapula) and the ribs.
Management of bone cancers
Bone cancer treatment includes therapy with medication or chemotherapy to reduce the size of the tumor and then follow up with surgery to remove the affected area of bone. Earlier bone cancer surgery involved removal of the limb altogether (amputation).
These days the affected part of the bone may be removed and replaced with metal implants. This is called limb-sparing surgery.
Bone cancer that is detected early and is confined to the bone is relatively easier to treat with a better outlook. On the other hand cancer that has spread to the bone marrow or to other organs like lungs, liver etc. is difficult to treat and chances of survival are relatively low.