Bone Metastasis

Overview

Types

Cancer affecting the bone is of two distinct types

1. Primary Bone Cancer:

This is cancer which arises in the bone itself‚ i.e. this cancer originates in the tissues of the bone. They are called Sarcomas. They are very rare tumors. The commonest bone sarcomas are Osteosarcoma, Ewing’s Sarcoma and Chondrosarcoma.

2. Secondary Bone Cancer:

A bone tumor caused by the spread of cancer of some distant organ or tissue, to any bone‚ is called as Bone Metastasis. They are also called as Bone Secondary‚ Bone Metastasis‚ SkeletalMetastasis or simply as “Bone or Skeletal mets” Secondary Bone Cancer is far more common than Primary Bone Cancer.

Often they are multiple at presentation‚ i.e. they may be found in more than one bone or/and at more than one location in a single bone‚ at the time of detection/diagnosis. Bone is a common site of metastasis for a number of different cancers. The cancers which spread most often to the bones are those from lung‚ breast‚ prostate‚ kidney and thyroid.

Symptoms

What are the symptoms of Bone Metastasis?

• Pain: Bone Metastasis is one of the most frequent and important causes of pain in people with cancer.
• Fractures: This is one of the most serious complications of Bone Metastasis. Bone Metastasis weakens bones in the region of the metastasis‚ making them vulnerable to fracture due to trivial causes.
• Swelling: This is not a usual presenting complaint in a patient with Bone Metastasis. By the time a swelling becomes obvious‚ the patient usually would have had complaints of pain in that region for some time.
• Spinal cord compression: This is perhaps the most dreaded complication of Bone Metastasis. This occurs when cancer metastasizes to the spine (backbone). The symptoms of spinal cord compression may range from, just pain‚ to complete paralysis and loss of sensation of the body below the level of the compression.
• High blood calcium levels. This is called as Hypercalcaemia. Symptoms of Hypercalcaemia could be nausea, vomiting, lethargy, moodiness, stomach pain, etc. If untreated, it can lead to coma.

Treatment

What is the treatment for Bone Metastasis?

The most important treatment for any metastasis is the effective treatment of the primary cancer with systemic medication‚ which may be in the form of chemotherapy‚ hormone therapy‚ systemic radiotherapy‚ etc. In addition to the cancer treatment‚ there are a variety of treatment options available for specific treatment of the Bone Metastasis.

Targeted treatment of specific Bone Metastasis is usually done only when they are symptomatic‚ have caused complications‚ or show signs suggestive of an impending complication. This may involve the use of radiotherapy‚ surgery‚ radiofrequency ablation‚ etc. Often more than one treatment modality may be employed.

The most important treatment for any metastasis is the effective treatment of the primary cancer with systemic medication (medication which is injected or ingested and therefore reaches all the tissues of the body through the blood).

This may be in the form of chemotherapy‚ hormone therapy in hormone sensitive cancers (e.g. breast cancer‚ prostate cancer‚ etc.)‚ systemic radiotherapy in cancers where it is useful (e.g. radio-iodine treatment in thyroid cancer)‚ etc.

In addition to the cancer treatment‚ there are a variety of treatment options available for specific treatment of the Bone Metastasis. Local treatment of Bone Metastasis is usually done only when they are symptomatic‚ have caused complications‚ or show signs suggestive of an impending complication.

Often more than one treatment modality may be employed. The following are some of the important treatment modalities that are useful in the management of Bone Metastasis.

1. Chemotherapy:

Chemotherapy is one of the most important modalities of systemic treatment of cancer. The exact chemotherapy regimen depends on‚ which cancer caused the metastasis. The most effective systemic treatment of the primary is also the best treatment for the secondaries‚ as they are basically made of the same tissue.

Chemotherapy may not be used in the treatment of all cases of Bone Metastasis. For example‚ in some types of cancer‚ effective chemotherapy may not be available‚ while in some situations‚ chemotherapy may not be considered safe for the patient. All aspects of a given case have to be considered‚ before deciding on the use of chemotherapy for the treatment of Bone Metastasis.

2. Hormone Therapy:

This is also called as Endocrine Therapy. This is one of the major treatment modalities in the management of certain types of cancer. Some cancers are sensitive to particular hormones in the blood‚ e.g. in some breast cancers‚ the cells have receptors for the hormone estrogen‚ which respond to the estrogen in the blood and stimulate the growth of these tumors.

Hormone Therapy uses drugs‚ which either prevent specific hormones from forming‚ or acting on the tumor cells; there by‚ inhibiting the growth of these cancers. Thus, hormone therapy can work in two different ways.

In one method‚ the level of the offending hormone in the blood is lowered by stopping or reducing its manufacture in the body‚ consequently stopping/reducing the stimulation of the cancer cells. In the other method‚ the receptors to the hormone on the cancer cells are blocked‚ which prevents them from getting stimulated by the hormone.

In both methods‚ the stimulation of the cancer cells by the offending hormone is interfered with‚ thus inhibiting the growth of these cancers. Some of the well-known hormone sensitive cancers are certain breast cancers‚ prostate cancer‚ endometrial cancer‚ etc.

3. Radiation Therapy:

Radiotherapy is a form of cancer treatment where a certain type of energy called as ‘ionizing radiation’ is used to injure or destroy cancer cells. ‘Ionizing radiation’is made of either powerful electromagnetic rays (X-rays/gamma rays)‚ or high energy sub-atomic particles like atomic nuclei‚ protons‚ neutrons‚ etc.

Radiotherapy is useful in relieving pain and controlling the growth of the Bone Metastasis. The response to radiotherapy is variable and depends on several factors‚ including the type of cancer causing the metastasis.

Radiotherapy is not administered to all Bone Metastases. The role of Radiotherapy in a situation of Bone Metastasis is‚ generally, to relieve the symptoms caused due to the disease in the bone. It is used to treat symptomatic (i.e.‚ painful) Bone Metastases‚ in situations where other options of treatment (chemotherapy and/or hormone therapy) are not available‚ or have not proven effective. In some cases‚ it may be used to prevent a complication like a fracture‚ or spinal cord compression‚ when such an event seems likely (although‚ not imminent – which would otherwise merit surgery as the treatment of choice).

Typically‚ radiation is administered to the site of Bone Metastasis in the form of ‘External Beam Radiotherapy’, either as a single treatment‚ or in around 5 to 10 treatment sessions (also called as fractions) over a week to 2–week period. It is a painless and non-invasive procedure – almost like getting an X–ray.

In some situations‚ where there are multiple Skeletal Metastases‚ external beam radiotherapy may be given to the entire upper or lower half of the body‚ and if necessary‚ 2 to 4 weeks later‚ to the whole of the other half of the body. This is called ‘Hemibody Irradiation’.

Another type of Radiation Therapy useful in treatment of Skeletal Metastasis is called ‘Radiopharmaceutical Therapy’or ‘Internal Radiotherapy’. This method uses systemically administered radioactive isotopes‚ which is delivered intravenously or through the mouth (injected or ingested). It is best indicated for treating patients with multiple symptomatic Skeletal Metastases.

In this form of treatment‚ bone seeking radioactive substances like strontium – 89 or Samarium – 153 are used‚ which accumulate in the regions of Bone Metastasis and give off radiation directly to the affected area‚ providing relief from the pain due to the metastases. A very effective and widely used Radiopharmaceutical Therapy is the use of radioactive–iodine (Iodine–131‚ which is avidly taken up by the thyroid cancer cells) in the specific treatment of metastases of some varieties of thyroid cancer.

4.Bisphosphonates:

This is a class of drugs‚ which is making news in the management of Bone Metastasis. These drugs slow the bone damage caused by metastases. They are used to decrease the risk of complications like fractures‚ and to lower the abnormally high blood calcium levels (hypercalcemia) seen in some patients with Bone Metastasis. It is also suggested that bisphosphonates reduce the pain due to Bone Metastasis.

5. Surgery:

The goals of surgery are‚ to preserve or restore the strength‚ stability and function of the skeletal system‚ alleviate pain‚ and preserve or restore the neurological function in cases of vertebral metastases with spinal cord compression. Surgery is usually the last resort in the treatment of Bone Metastasis.

There are, however‚ a few situations where surgery is the best way to treat Bone Metastasis:

• Management of fracture or impending fracture: Surgery is the best way to treat a Pathological Fracture caused by Bone Metastasis. It offers the quickest relief from this difficult situation. Surgery is also the best way to avoid a fracture and therefore‚ its consequences‚ in situations where a fracture appears imminent.
• Relieving spinal cord compression and/or stabilization of the spine: Spinal cord compression with paralysis or weakness in the lower part of the body is perhaps the most devastating of all complications of Bone Metastasis. Spinal metastasis can also cause to instability of the spine which can cause excruciating pain. Both these conditions can confine the patient to a bed, unable to get up and be independent. In patients presenting with symptoms of spinal cord compression, surgery is the best option for relieving the pressure on the spinal cord quickly and therefore, perhaps offers the best chance of recovery of the lost power and sensation. It is also the best way to relieve the pain due to instability of the spine. Certain cases of painful vertebral body metastasis can be treated with percutaneous vertebroplasty procedures (injection of bone cement into the vertebral body through a special needle).
• Very large bone metastasis in the extremity: Sometimes‚ the patient may come very late for the management of Bone Metastasis. The metastatic bone disease may be very large and painful. Some of these tumors may break through the skin and cause profuse bleeding which cannot be easily controlled. In all these conditions‚ amputation is a very useful choice of surgical treatment and can offer tremendous relief from pain and disability

6. Radiofrequency Ablation (RFA):

In RFA‚ heat is generated at the tip of a probe that is inserted into the tumor under image guidance (fluoroscope or CT scan). This local heat‚ which is generated due to ionic agitation and resultant friction caused by a high frequency alternating current flowing through the electrodes at the tip of the probe, kills the tissues around the probe tip.

RFA is a very effective alternative for treating small‚ deep seated‚ painful bone metastasis‚ especially in situations where surgery is not feasible. It can often prove helpful in controlling pain in Bone Metastasis‚ which has failed to respond to radiation and powerful painkilling medication.

Dr. Chetan Anchan is an expert and well-known orthopedic surgeon and oncologist from Mumbai. He has vast experience in treating all types of Malignant and Benign, Bone and Soft Tissue Tumors, and Skeletal Metastases.

Dr. Chetan holds an extensive expertise in managing and treating various bone malignancies.

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Frequently Asked Question On Bone Metastasis