Cancer development occurs whenever there is excessive and uncontrolled proliferation of cells in any organ. When this uncontrollable and unwanted division occurs within a bone, it is called bone cancer. Bone cancer can be either primary or secondary. Primary bone cancer originates in the bone cells while secondary bone cancer develops elsewhere and spreads to the bone.
Both of them may have similar signs and symptoms, but the cause and the treatment protocols will vary. Here, we will discuss about the primary type of bone cancer.
Signs and symptoms
As the tumour cells start occupying the limited space available inside the bone, you may observe the following signs and symptoms:
- Persistent bone pain
- Palpable mass
- Tenderness over the affected bone
- Swelling over the affected bone
- Frequent and easy fractures
- Unintentional weight loss
If the tumour cells have metastasised to some distant organ then the signs and symptoms will vary depending on the organ involved.
Stages of Bone Cancer
There is a total of four stages depending upon the size and location of the tumour along with the presence or absence of metastasis:
- Stage 1: Smaller, low-grade tumour + no metastasis
- Stage 2: Larger, high-grade tumour + no metastasis
- Stage 3: More than one tumour in the same bone
- Stage 4: Spread to distant organs
Types of Bone Cancer
There are many types of bone cancers depending on the type of cell it develops from; the most common ones are:
- Osteosarcoma: This is cancer with bone-producing cells. It is the most common type of bone cancer and mostly affects the long bones of arms and legs. It is usually seen in children and young adults.
- Chondrosarcoma: This is cancer with cartilage-producing cells in the tumour. It is the second most common type of bone cancer affecting the pelvis, arms and legs. It usually affects middle-aged and old aged people.
- Ewing’s sarcoma: This usually affects the age group between 5 to 20 years. It’s a rare kind of cancer affecting the pelvis, arms and legs.
- Multiple myeloma: this is the cancerous proliferation of the cells of the bone marrow usually affecting the older population and is not a true cancer of the bone.
Secondary bone cancer can develop from metastasis commonly from the following types of cancer:
- Prostate cancer in males
- Breast cancer in females
- Lung cancer
Very rarely benign tumours of bone also progress to turn malignant.
- Examples of benign tumours are:
- Osteoid osteoma
- Chondromyxoid fibroma
Causes of Bone Cancer
There is no specific cause which can definitively explain the development of bone cancer. However, many risk factors have been identified:
- Radiation exposure causes irreversible DNA changes in cells which can later progress to bone malignancy.
- Bone diseases: Paget’s disease of bone can very rarely progress to malignancy.
- Cancer history: Radiation is a part of cancer treatment and causes an increase in the risk.
- Hereditary factors: Li-Fraumeni syndrome and an eye cancer called retinoblastoma may increase the risk of bone cancer development.
The cancerous tumour within the bone is seen with the help of various scans. These scans are done to measure its size and infiltration into the surrounding tissue:
- X-ray: An abnormal growth can be visualised.
- CT scan: Helps in locating the extent of disease.
- MRI: Helps visualise the cancer cells in other soft tissues.
- PET-CT: It helps to locate the metastasised cells.
- Bone scan: A radioactive substance is injected into the veins which is then taken up by the bones having a higher cell division rate (usually the malignant cells). This can be viewed by illumination. It helps to locate the exact location and size and spread of the tumour.
- Biopsy: This is a confirmation test for bone cancer. In this, a small sample of the suspected cancer tissue is taken out and visualised under a microscope for malignant changes. This not only confirms the presence or absence of malignancy but also helps in the assessment of the grade of the tumour.
There are two ways in which the biopsy sample can be obtained from the affected bone:
- Needle biopsy: This procedure is usually done under local anaesthesia. In this, a small needle is inserted into the bone tissue to take the sample.
- Open biopsy: In this, instead of using a needle, the bone is cut open and the sample is taken out. It is done for cancers where samples cannot be obtained by core needle biopsy under general anaesthesia.
Complications of Bone Cancer
- Restricted mobility
- Recurrent fractures
- Stunted growth and development in a child
- Heart, liver and lung problems due to radiation therapy
- Rarely loss of hearing due to chemotherapy
- Risk of development of other cancers
Treatment depends on the type of cancer, the extent of spread, and the overall health of the patient.
- Surgery: It is usually done for low-grade tumours. This surgery can be of two types depending upon the amount of bone involved. Firstly, limb-sparing surgery, where a small portion of the bone is removed and reconstructed by metallic implants. This preserves the mobility of the person.
Secondly, For high-grade and extensive tumours, the entire limb or bone is amputated.
- Chemotherapy: Strong medicines targeting the rapidly dividing cells are injected into the bloodstream. It kills the cancerous metastasised cells.
- Radiotherapy: High energy waves are passed through the affected organ to kill the cancerous cells.
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