Metastatic Lesions of the Extremities - Causes, Symptom, and Treatment

Introduction

Metastatic disease of the bone is the third most common disease of the body. The term metastasis refers to the migration of cancer cells from the site of origin to the bones. The patient mainly shows symptoms of pain and fracture as the first line of symptoms. Fractures of the bone occurring due to bony metastatic lesions comprise almost 10 to 30 percent of the cases. It is important to study the cause of bony metastasis to decide on the treatment plan.

What Are Metastatic Diseases?

Metastatic diseases are secondary diseases arising in the bone due to the migration of cancer cells from the site of origin. The commonly occurring metastatic lesion of the bone is primary tumors originating from the lungs, kidney, bladder, prostate, breast, and cancers of the muscle and lymph nodes.

How Does Metastatic Disease of the Extremities Occur?

Bone metastasis occurs in multiple sites, commonly arising from the axial part of the bone. The spread of the cancer cells occurs through the bone marrow and bloodstream, which produces the red blood cells (RBC), and vertebral column. The condition which provides a favorable atmosphere for the tumor cells is when the tumor cells migrate and stick to the blood vessels, which is accompanied by a blood-rich environment that aids in cellular growth. The cancer cells which need to migrate undergo a transition from their original structure and modify their shape and form, and this process is called an invasive phenotype. This modified structure affects the quality of the bone, making it more fragile.

What Are the Causes of Metastatic Diseases of the Extremities?

The common causes of metastatic disease of the extremities are carcinomas (cancer) of the breast, lungs, thyroid, kidney, and prostate from which the primary cells travel affecting the extremities and causing a secondary lesion.

How Common Are Metastatic Diseases of the Extremities?

The spread of cancer to the bones is the third most common metastatic disease. The spread of cancer cells in bones is seen in people above the age of fifty years. The common sites of extremities showing the spread of cancer are the spinal bone, femur (thigh bone), and humerus (bone of the arm). While the proximal part of the bone shows common metastasis, the distal part of the extremities shows rare occurrence.

What Are the Signs and Symptoms of Metastatic Diseases of the Extremities?

Patients show a history of pain and fracture due to the weakening of the bone. Metastatic diseases are seen in 10 to 30 percent of cases, in which 90 percent require surgical management. Patients also experience confusion, muscle weakness, frequent urination, increased thirst, nausea, dehydration, and increased blood calcium levels.

How Is Metastatic Disease of the Extremities Investigated?

There are various examination methods done to confirm the presence of metastatic diseases of the extremities, and they are:

• Physical Examination: Patients show evident neurological defects with compromised function, pain, or numbness. These symptoms occur due to compression of the spinal cord and the spread of tumor cells in the spine.

• Laboratory Investigation: Multiple laboratory tests are done as this mainly affects the blood spread. The laboratory tests include blood serum, calcium levels, and urine tests.

• Radiographic Examination (X-Ray): These are two-dimensional images used to detect any abnormality or fracture on the bone along with bone density.

• Computed Tomography (CT): CT scans are three-dimensional images used to study the structure of the bone. CT scan helps us know about the bone's bony boundaries and structural integrity.

• Fluorodeoxyglucose-Positron-Emission-Tomography (FDG-PET) Scan: PET scan is a type of scan where a dye is injected and circulated in the system. This system is used to find any cancer-related changes or abnormal growth occurring within the bone.

How Is Metastatic Disease of the Extremities Treated?

Management of metastatic diseases of the extremities is always a medical emergency and needs proper treatment. The treatment options mainly aim to restore the patient’s proper functional activity. The methods used in treating the patients are:

1. Medical Management: The first and foremost level of managing the patient is to handle the pain. Patients with Metastatic disorders experience maximum pain and are put under nonsteroidal anti-inflammatory drugs (NSAIDs), opioid painkillers, and bisphosphonate therapy (this is the method of treating the patient with oral phosphorus supplements as they are more prone to weakening of bone and calcium loss). Irrespective of surgical or radiological management, sustained chemo, and hormonal therapy is indicated.

2. Radiation Therapy: This is the method of treating cancer cells using high-intensity radiation waves and killing them. Radiation therapy kills the targeted cancer cells and prevents progression and transmission. More than 50 percent of the patients show pain relief for more than six months of duration.

3. Surgical Management: Surgical management for treating metastatic diseases differs from other levels of treatment. From correcting the infected bone to fracture management, everything falls under surgical management. The main protocol for surgical management is to protect the length of the bone and prevent failures. The surgical options that are usually done are:

1. To stabilize the fractured segment: Cancer patients are more prone to bone weakness. Fracture of the bone due to weakness is extremely common. It is important to rehabilitate the fractured segment and restore its function.

2. To remove the affected segment: The affected segments detected with tumor cells are removed and replaced with grafts and stabilized using screws and plates. This is done using locked compression plates which reduce the risk of loosening.

What Is the Prognosis of Metastatic Diseases of the Extremities?

Irrespective of the type of tumor, the prognosis of the disease depends on multifactorial outcomes. The level of cell modification and blood serum modifications alter the prognosis. Hence, the prognosis of the disease is usually arbitrary or varies from patient to patient. With good clinical management, the survival rate of patients is seen to improve from 3 to 12 months.

Conclusion:

Metastatic disease of the bony extremities is a complicated disease that needs immediate management because the long bones produce and transmit blood to all body parts. The spread of cancer cells in these bones can be more complicated. The bones need proper care and monitoring as they are very fragile and prone to fracture. With extreme care and intensive surgical management, longevity and quality of life can be altered and improved.