Bone cancers may originate in the bone or may originate elsewhere in the body and spread to the bones. The first type is called Primary bone cancer while the second is called Secondary bone cancer. All types of bone cancer are very rare but Primary bone cancers are particularly rare. 1-6
Types of bone cell
The bone is a dynamic organ unlike its appearance of a hard inert organ. There are cells within it, as well as fibers or tough tissues called collagen and minerals like Calcium and Phosphates.
The cells include Osteoblasts, Osteoclasts and Chondrocytes. The osteoblasts are cells that multiply regularly to provide the growth and structure of the bones.
The Osteoclasts help in removal or dissolution of the excess bone tissues. This helps in moulding a remoulding of the bone to suit the structure and function.
Chorndrocytes give rise to the cartilage tissues that cap the ends of the bones especially at the joints.
All these cells are constantly growing and dying to make the bone an organ like any other in the body. Cancer occurs when these cells have abnormalities in their growth cycles and grow unimpeded.
Types of bone cancer
Primary bone cancers may affect the bone cells. These cancers are all termed “sarcoma”. A sarcoma is a cancer that originates from cells that construct the connective tissues (supporting tissues) of the body. This includes cells of the bone, muscle, cartilage, ligaments, etc.
Types of bone cancers include osteosarcoma, Ewing's sarcoma, spindle cell sarcoma and chondrosarcome.
This is the most common type of primary bone cancer but is rare in the general population. In the UK around 150 new cases are diagnosed each year.
Osteosarcoma commonly affects children and young adults between ages 5 and 20 years. Among children Osteosarcoma is the third most common cancer in young people after leukaemia and brain tumours.
The male:female ratio is 1.4:1. It arises from bone-forming cells or osteoblasts.
This cancer affects large bones like thigh bone (femur) or the shin bone (tibia) more commonly than other bones. It typically develops in the growing ends of the bone near the knee and may also affect the upper arms bones. However, any bone can be affected.
Ewing's sarcoma is detected in around 100 people each year in the UK. This type of cancer also affects children and young adults predominantly with most cases seen in people aged between 10 and 20 years. However, around 1% of cases may be detected in those over 20 as well.
The condition is extremely rare over the age of 40. It is very uncommon in the African and Asian population. The male to female rate of incidence is 1.5:1. This cancer also affects the thigh bone, shin bone and the pelvis or hip bone.
Spindle cell sarcoma
This is a rare type of bone cancer with an estimated 80 cases each year. The cancer is similar to osteosarcoma in terms of appearance, symptoms and management protocols and plans. However, this type of cancer is commonly seen in adults over the age of 40.
This type of cancer occurs in the Chondrocytes and is rare with around 80 cases diagnosed each year in the UK. This cancer may be found in the middle aged and those between ages 40 and 50. Males and females are equally affected.
The most common sites of Chrondrosarcoma are the pelvis or hip bone, thigh bones, upper arm bone (humerus), shoulder blade (scapula) and the ribs. They may arise from pre-existing lesions like osteochondromas and chondromas or they can be primary.
Rare types of primary bone cancer
Other rare types of primary bone tumour include:
- fibrosarcoma (affects the fibrous tissues in the leg, arm or jaw)
- malignant fibrous histiocytoma (affecting connective tissues)
- angiosarcoma (affects the blood vessels)
- chordoma (spine and base of the skull)
- malignant giant cell tumour
Secondary bone cancer
Secondary bone tumors are those that originate from other cancer sites. These may be multiple or single.
The most common sites from where bone cancers or metastasis may occur are breast, prostate, lung, kidney and thyroid. In children common sites from where bone cancer may originate include Wilm’s tumor and neuroblastoma.