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.
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
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.
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.
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.
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.
Cancers usually begin when the growth cycle of a cell is abnormal. Normal cells have genetic blue prints or guidelines that regulate their growth, attainment of maturity, reproduction and functions and ultimately death. The DNA provides these basic information and instructions.
If there is a change in the DNA at a point it is called a mutation. This change may alter the instructions that control cell growth. This ultimately may lead to the death of the cells or even to an uncontrolled growth of the cells.
The cells continue to grow without stopping or dying and also reproduce uncontrollably. This leads to formation of a lump of tissue called a tumour. 1-8
In some cases this tumor may be harmless or slow growing and is termed benign. This tumor, apart from pressing on the surrounding tissues may not affect the person. In some cases the mutation of the DNA may lead to cancer.
Left untreated or unchecked the cancer cells may spread to other organs from the affected area of the bone. The spread may affect the bone marrow that lies within the inner core of the bone and is responsible for formation of blood cells or into other organs via blood vessels.
Most primary bone cancers affect children and young people in whom there is a growth spurt and rapid bone growth.
Bone cancers commonly affect the fast growing ends of the bones. The ends of the bones are the fastest growing sites of the bone where the osteoblasts are most active.
The exact cause of bone cancers that originate from the bone (Primary bone cancers) is not known. It is speculated that some risk factors may raise the chance of getting bone cancers. It must be remembered that primary bone cancers are very rare.
These risk factors include:
Age - The risk of osteosarcoma is highest during the teenage growth spurts
Height – There may be link between tall children and osteosarcoma.
Sex - Osteosarcoma is more common in males than in females.
Ethnicity - Osteosarcoma is slightly more common in African Americans than in whites.
Those who have been exposed to radiation or radiation therapy previously are at a higher risk of bone cancers.
Those with Paget’s disease of the bone are also at risk of bone cancers. However, the risk of bone cancers in individuals with Paget’s disease is less than 1%. Chondroma also increases the risk of osteosarcoma.
There is a rare genetic condition called Li-Fraumeni syndrome. This affects 1 in every 142,000 people and may raise the risk of bone cancers. Hereditary multiple exostoses (HME) and inherited breast cancer may also raise the risk of bone cancers.
Babies with a rare type of childhood cancer which develops in the eye called retinoblastoma have a higher risk of bone cancers.
Ewing’s sarcoma has been seen three times more commonly in babies who are born with an umbilical hernia. The cause of this association is as yet unknown. Umbilical hernia occurs in some babies at birth when their abdominal contents like intestines tend to protrude out from their navel that refuses to close. The risk of Ewing’s sarcoma in these babies however is very small with only one in 110,000 children with an umbilical hernia going on to develop Ewing’s sarcoma.
Bone cancer has often been linked to injuries to a limb but this association is not proven.
The most common symptom of bone cancer is bone pain. The affected area is tender to touch and the child is often seen avoiding the use of the joint or limb with the affected bone. The pain becomes chronic and may worsen during the night and affect sleep.
Ewing sarcoma patients complain of rapidly worsening bone pain. This bone pain may be mistaken for arthritis in older adults and “growing pains” in children and teenagers.
Apart from pain and tenderness there may be swelling and redness and a noticeable lump over the affected area. If the affected area is near the joint, movement at the joint may be stiff or restricted.
Bones affected with cancer are also weak and brittle and may fracture or break easily with minor injuries or trauma.
Other less common but more serious symptoms include:
high temperature (fever) of 38C (100.4F) or above
sweating, usually at night
unexplained weight loss etc.
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
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.
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.
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.
Other rare types of primary bone tumour include:
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.
Children and young adults with symptoms of bone cancer present to their physician with bone pain, swelling, lump or a fracture. Diagnosis is made on the basis of physical examination and detailed imaging studies. 1-6
Diagnosis of bone cancer includes taking a medical history, physical examination and so forth.
History of bone pain, radiation exposure, Paget’s disease, retinoblastoma and umbilical hernia at birth is important. Family history of Li-Fraumeni syndrome or HME needs to be evaluated as these may raise the risk of bone cancers.
A physical examination shows the signs of a bone tumor. The long bones (especially at the ends) like the thigh bone (femur), shin bone (tibia), upper arm (humerus), pelvis (hip bone) are commonly affected. However, other bones may also be affected. A complete physical examination reveals swelling, tenderness, joint movement restriction etc.
Routine blood tests are advised. If there is affliction of the bone marrow due to spread of the cancer there may be anemia, low white blood cell or platelet counts.
Blood biochemical tests may show increase in an enzyme called alkaline phosphatise in patients with osteosarcoma
This is the most common and most cost effective investigation advised when a bone condition is suspected. The patient who presents to the physician with a fracture may have an underlying bone cancer that may be suspected on an X ray. If the X ray is suggestive of bone cancer the patient is referred to a specialist for further evaluation and management.
This is the most definite method of detecting bone cancer. Biopsy involves taking a small sample of the affected area of the bone and staining it with suitable dyes on a slide and examining the cells of the sample under a microscope in the laboratory.
Biopsy is used to detect the type of cancer, the stage or grade of the cancer and how aggressive the cancer is. This helps in planning management of the cancer and also helps in predicting the outcome of the cancer.
Biopsy of the bone may be taken by one of the two methods - core needle biopsy or open biopsy. A core needle biopsy is performed after applying local or general anesthesia. A thin needle is inserted into the bone and a sample of tissue is removed.
An open biopsy is usually performed under general anaesthesia. The surgeon makes an incision over the affected bone and removes a larger section of the bone for analysis.
MRI scan is another imaging study that uses a strong magnetic field and radio waves to look at the bones and the organs of the body. This may be advised to detect the size and spread of any cancerous tumour within the bone.
A CT scan also involves taking a series of X-rays that look at the size and extent of spread of the cancer. CT scans of the chest may reveal spread of the bone cancer to the lungs.
A bone scan or Bone scintigraphy using technetium99 may be prescribed. This used a small amount of radioactive material (technetium99) that is injected into the veins of the arm.
Abnormal areas of bone will absorb the material at a faster rate than normal bone. A special camera is then used to take pictures of these “hot spots” where the dye is concentrated.
A Positron emission tomography (PET) scan may also be performed.
After diagnosis and confirmation of the cancer the cancer is staged into various stages. Staging helps to decide on the treatment and also helps to determine the outcome of the cancer.
Stage 1 for example is when the cancer is low grade and has not spread beyond the bone.
Stage 2 is when the cancer has still not spread beyond the bone but testing shows that it is high grade cancer and has the potential for spread.
Stage 3 occurs when the cancer has spread into other parts of the body, such as the lungs.
Bone cancer is usually treated by a team of health care providers. The team includes:
an orthopaedic surgeon who specializes in conditions of the bones and joints
a clinical oncologist or cancer specialist
pain relief specialist or palliative care specialist
a cancer nurse
a social worker
These are termed multi-disciplinary teams that assist people with bone cancer. 1-6
Bone cancers are usually treated with three modalities of treatment:
Chemotherapy – with the use of anticancer drugs that are used to shrink the tumors
Most patients need a combination of these therapeutic approaches for management of bone cancer. Different types of bone cancer are usually treated in a similar way.
The treatment usually begins with chemotherapy to prevent spread and shrink the tumor and thereafter surgery may be carried out to remove the section of cancerous bone.
Earlier surgery meant removal of the affected limb altogether – or limb amputation. These days it is possible to reconstruct the part of the bone that is removed using metallic implants. This is called limb sparing surgery.
Radiotherapy is used after surgery to kill any residual cancer cells. It is helpful in some types of cancer (such as Ewing’s sarcoma, for example).
Cancer killing medications are used to kill the tumor cells and shrink the tumor. This may be given before surgery, in combination with radiotherapy before surgery (chemoradiation) as is preferred in Ewing sarcoma, after surgery to prevent the cancer from returning and to control the symptoms in very advanced and non-curable bone cancers.
Chemotherapy may be given in cycles. Patient may or may not be admitted to the hospital but may have to visit the day care centers where the drug may be injected into their veins using infusions.
A cycle involves taking the chemotherapy medication for several days followed by a gap of a few weeks to allow the body to recover from the effects of the treatment.
A low grade cancer requires less number of chemotherapy cycles than a high grade tumor.
Medications that are used in bone cancer chemotherapy include:
Methotrexate with Leucovorin
Common side effects include:
loss of appetite
loss of hair
risk of infections
Since bone cancers affect children and young people the risk of infertility after chemotherapy should be considered and patients or their guardians should be counselled regarding choice of sperm or egg storage for future fertility choices.
Radiation therapy uses high energy X-ray or gamma ray beams to kill the cancer cells. This may be used before and after surgery to treat bone cancer.
Radiotherapy sessions may also be administered in cycles five days a week with a break from treatment over the weekends. Side effects of radiation therapy include skin burns, rashes, weakness, nausea, loss of hair etc.
Limb-sparing surgery is preferred if the cancer has not spread beyond the bone, and the affected bone itself is in an easily accessible position like in one of the arms, legs, shoulder, hip etc.
The surgery involves removing the section of affected bone and a bit of the surrounding healthy bone (just in case the cancer has spread to the tissues) and replacement of the part of the bone with a metal implant called prosthesis.
As an alternative bone grafts from another part of the body may also be used as a replacement.
If the cancer has affected a joint like the knee, elbow or shoulder joint, an artificial joint may have to be placed. The artificial joint is usually a combination of plastic, metal, and ceramics.
Amputation is needed if the cancer has spread beyond the bone and affected blood vessels and nerves, skin or if the limb sparing surgery has failed. Amputation is also opted if the bone that is affected is not easily accessible like the ankle joint.
Patients who require an amputation need counselling and may need help of an occupational therapist and counselling for opting an artificial limb.
Some agents have been developed for use against bone cancers. These originate from the cells of the body and are thus termed biological therapy. These target the cancer cells selectively and thus cause less side effects than chemotherapeutic agents.
A new medication called mifamurtide has recently been approved for the treatment of high-grade osteosarcoma. This agent is an immune macrophage stimulant. It acts by stimulating the immune system to produce specialised cells that can kill the cancer cells selectively. This means less side effects than seen with conventional chemotherapy agents.
Mifamurtide is given after surgery and also in combination with chemotherapy. It serves to kill any remaining cancerous cells and to help prevent the cancer from returning.
Common side effects include nausea, vomiting, headache, constipation, allergies, muscle and joint pain, hearing loss, blurring of vision etc.
The outcome of bone cancer is determined by survival for at least five years after diagnosis. For localised osteosarcoma and Ewing’s sarcoma five year survival is seen in around 60% and 70% people respectively.
Those in whom the osteosarcoma or Ewing’s sarcoma has spread the chances of five year survival is only 10% and 30% respectively.
For those with low-grade chondrosarcoma 8 out of 10 people may survive five years after diagnosis and for high-grade chondrosarcoma only 3 out of 10 people may survive five years after treatment.