Sarcoma of the Lower Limb - Symptoms, Risk Factors, and Treatment

Introduction

Sarcomas include a vast group of malignant cancers affecting around 7 to 15 percent of cancers in kids and one percent of adult cancers. Most extremity sarcomas develop in the lower extremities, the legs. This leads to an increased rate of lower extremity reconstruction after excision due to sarcoma. Of all the sarcomas of the lower limb, soft tissue sarcomas are the most prevalent.

What Is a Sarcoma?

A sarcoma is a type of tumor that occurs in the bone or the soft tissues of the body, such as fatty tissues, cartilage, muscles, blood vessels, nerves, tendons, ligaments, and other connective tissues of the body. Sarcomas are characterized on the basis of their location. The treatment and outlook depend on the type and stage of cancer. Sarcoma affects both children and adults.

What Are Lower Limb Sarcomas?

Lower limb sarcomas are a rare but aggressive cancer. Around one percent of all cancerous tumors are sarcomas, and 41 percent of them develop in the extremities. The lower limb accounts for 75 percent of all cases of malignant sarcomas. A delay in detecting such cancers can lead to the loss of a limb or, eventually, life. Therefore, radiological detection is of key importance in detecting such carcinomas.

What Are the Symptoms of Lower Limb Sarcomas?

A lower limb sarcoma may be asymptomatic in the earlier stages. However, in the later stage, it might lead to the following symptoms:

• A lump or swelling in the lower extremities.

• A lump that is growing in size.

• Recurrence of the lump that has already been resected.

• A lump presents deep within the muscle.

• Pain in case the lump puts pressure on the nerves.

What Are the Risk Factors of Lower Limb Sarcomas?

Associated with a risk factor does not necessarily mean that one will get cancer, but it increases their chance of developing it. For example, the following are the risk factors of soft-tissue sarcomas:

• Radiotherapy treatment in the past.

• Chronic lymphedema in the arms and legs.

• Exposure to chemicals such as thorotrast, vinyl chloride, or arsenic.

• HIV (human immunodeficiency virus) infection.

• Certain inherited disorders, such as:

  • Li-Fraumeni Syndrome.
  • Von Recklinghausen disease.
  • Gardner syndrome.
  • Nevoid basal cell carcinoma syndrome.
  • Tuberous sclerosis.
  • Werner syndrome.

How Are Lower Limb Sarcomas Diagnosed?

• Biopsy: The Sarcoma of the lower limb is a cancerous tumor, and a biopsy is recommended to diagnose it correctly. The type of biopsy is based on the size and location of the tumor. A biopsy is the removal of a small part of the tumor tissue to be examined under the microscope for the presence of cancerous cells. The following types of biopsies may be carried out:
  • Core Needle Biopsy - In this biopsy, tissue is removed with the help of a wide needle. Then, it is guided by MRI (magnetic resonance imaging), CT (computed tomography) scan, or ultrasound. Several tissue samples are taken for examination.
  • Incisional Biopsy - This biopsy is carried out if the core needle biopsy cannot be performed. In an incisional biopsy, a part of the lump is removed. In a biopsy, the samples are taken from the tumor, lymph nodes, and other areas where the cancer has spread. Then the collected tissue samples are examined to understand the stage and grade of the tumor.

• Immunohistochemistry - This is a laboratory test in which antibodies are used to check for the presence of certain substances known as antigens in the tissues. The antibodies are linked to a certain enzyme or dye. This enzyme or dye becomes activated on binding with the corresponding antigens, making the antigen visible under the microscope. Immunohistochemistry is helpful in differentiating one cancer from another, thereby helping diagnose cancer.

• Flow Cytometry - This test is used to measure the number of cells and their characteristics like size, shape, and presence of certain markers on the cellular surface. The cells that are collected from the blood, bone marrow, or other places are stained with the help of a dye, placed in a fluid medium, and passed through a light beam. The result is obtained on the basis of the cellular reaction to the light beam.

• Molecular Profiling - This test examines the tissues, blood, or other body fluids for the presence of certain proteins, genes, or other cancerous substances. It is also used to detect the presence of any changes in the genes that might increase a person's risk of developing cancer. This procedure can be carried out with biopsies for diagnosing certain cancers. It can also help in the treatment plan, identifying the prognosis, or predicting the metastasis and recurrence of cancer.

• Light and Electron Microscopy - This is a laboratory test in which the cells are viewed under high-powered microscopes to identify any changes in them.

• Cytogenetic Analysis - In this test, the chromosomes - a structure containing the genetic material of an organism, in a tissue sample are checked for the presence of any alterations. Changes include missing or broken, excess number, or rearranged chromosomes. Cancer could also be due to changes in the chromosomal structure or number. The cytogenetic analysis thus helps in diagnosing cancer, chalking out a treatment plan, and accessing the prognosis of the treatment.

• Fluorescence in Situ Hybridization (FISH) - This is a test that examines and counts the genes in the tissues. Genetic material containing dyes is prepared in the laboratory and incorporated into the patient's tissue sample. On adding to the patient's chromosomes, these light up when viewed under the microscope. This test also helps in detecting cancer.

How Is Sarcoma of the Lower Limb Treated?

• Surgery - Surgery is the common treatment for the sarcoma of the lower limb. In the past, amputation was a common surgical treatment for lower limb sarcoma. This would reduce the chances of recurrence. However, chemotherapy and radiotherapy have given rise to limb-salvage surgery, which involves reconstruction as a method to save the limb.

• Radiation - Radiation therapy uses strong radiation to shrink and kill the tumor before, during, and after surgery.

• Chemotherapy - Chemotherapy uses strong drugs to kill cancerous cells.

• Targeted Drug Therapy - Targeted drug therapy attacks specific cells and is better than chemotherapy with regard to toxicity.

Conclusion

Sarcomas of the lower limb are quite rare but aggressive. There are several types of sarcomas of the lower extremities. Treatment is often by surgical reconstruction, radiation, chemotherapy, or targeted drug therapy. The outcome for lower limb sarcoma is better than the other tumors as they are compliant with surgery as compared to the other tumors. However, there are chances of recurrence despite surgery. Nevertheless, prompt diagnosis and treatment can go a long way to a good prognosis.