Definition and Overview

Sarcomas are cancerous tumours that arise from cells that hold the body together (connective tissue). It is referred to as rhabdomyosarcoma if it affects the muscles, osteosarcoma if it develops in bones, and liposarcoma if it is found in the nerves, blood vessels, and fat. Because these connective tissues are found in different parts of the body, sarcoma cancer can occur anywhere. However, the most frequently affected are the limbs where the majority of the body’s connective tissues are found.

Adult cancer sarcoma is very rare and accounts for approximately 1% of all adult cancers. However, sarcoma is prevalent in children and is responsible for about 20% of all childhood cancers.

Sarcomas are divided into two main groups: soft tissue and bone sarcomas. Soft tissue sarcomas are more common than the latter. Sarcomas are further sub-classified based on their location. Some of these include:

  • Synovial sarcoma – A type of soft tissue sarcoma that occurs in the extremities often near the tendon sheaths and joint capsules.

  • Ewing's sarcoma – Commonly occurs in bones but can also affect muscles and cartilage. It is often diagnosed in the pelvis, thighbones, shoulder blades, and ribs.

  • Uterine sarcoma – A type of gynae sarcoma that can also affect other parts of the female reproductive system including the vagina, ovaries, and fallopian tubes.

  • Gastrointestinal stromal tumours (GIST) – This is a common type of sarcoma that develops in the gastrointestinal tract. It can also affect the small bowel and the stomach.

In general, patients with sarcoma tend to be younger than the majority of cancer patients. 16% of patients with bone or soft tissue sarcoma are below 30 years old while 37% are aged less than 50 years.

Sarcomas can spread to surrounding tissue and even distant organs of the body resulting in a condition called metastatic sarcoma. Generally, the 5-year survival rate for localised bone and soft tissue sarcoma is about 65%.

Causes of the Condition

As with other types of cancer, the reasons why sarcomas develop are not yet fully understood. However, scientists have identified common characteristics that sarcoma patients share. These characteristics, which are believed to increase one’s risk of developing the disease, include:

  • Exposure to chlorophenols in wood preservatives and phenoxyacetic acid in herbicides

  • Exposure to high dosage of radiation for the treatment of another type of cancer

  • Family history of sarcoma

  • Inherited diseases, including neurofibromatosis and Li-Fraumeni syndrome

  • Paget’s disease

  • Age – Although sarcoma can occur in people of any age, it is often diagnosed in adults under the age of 50

  • Weakened immune system – Some HIV patients develop Kaposi sarcoma, a malignant tumour that arises from cells lining the lymph or blood vessels.

Key Symptoms

Sarcoma symptoms are hardly noticeable at the beginning or when malignant tumours start to form. The first symptom is usually a painless lump. If the tumour grows quite large, patients may experience pain or soreness as the tumour presses on nearby nerves and muscles. Other symptoms include uncomfortable swelling and limited mobility.

Different subtypes of sarcoma also have other symptoms. For example, GIST may cause blood in stools or vomit, fatigue, fever at night, and anaemia while uterine sarcoma may cause vaginal bleeding.

Who to See and Types of Treatments Available

Soft tissue tumours are diagnosed with a surgical biopsy, in which tissue sample is removed from the tumour and analysed under a microscope. Osteosarcoma, on the other hand, is diagnosed using imaging tests including magnetic resonance imaging (MRI) and bone scans. Since the disease has the tendency to spread to other parts of the body, chest x-ray and computed tomography (CT) scan of the lungs are also performed to detect lung metastases. The results of diagnostic tests provide doctors with crucial information about the severity of the condition allowing them to carefully and effectively plan the treatment.

Treatment of sarcoma tumours involves a multidisciplinary team composed of cancer specialists (medical and radiation oncologists), surgeons, pharmacists, physician assistants, and other healthcare professionals. Malignant sarcomas, just like other types of cancer, are often treated with a combination of therapies that include the surgical removal of the tumour and adjuvant therapy (either chemo or radiation therapy). Small, low-grade sarcomas are often removed with surgery alone, which means that patients may no longer need to undergo chemotherapy. However, for those with high-grade tumours that are larger than 2 inches, multimodality therapy (surgery and chemotherapy or surgery and radiation therapy) is often necessary. Chemo and radiotherapy can be used before or after the surgery. They are often recommended before the surgical procedure if the tumour is quite large and needs to be shrunk first. Biological therapy, which stimulates the patient’s immune system to fight cancer, is also being used for the treatment of some sarcomas including GIST.

Most sarcomas of bones and joints are often removed using a surgical method called limb-sparing technique to help ensure that the patient does not suffer from long-term disability. The removed portion of the bone is then replaced with an allograft (bone taken from a cadaver) or a metal implant or a combination of two. Occasionally, due to the tumour’s size and location, amputation is necessary for complete cure.

New therapies are continuously being discovered to improve sarcoma prognosis. One of them is the use of olaratumab, an FDA-approved drug for patients who are not healthy enough to undergo surgery or radiation therapy. This treatment blocks growth-promoting signals in cancer cells.

Throughout the treatment process, various tests are performed on a regular basis to monitor the patient’s health with a special focus on their liver, kidneys, and heart. Their body’s response to treatment is also monitored and if needed, adjustments are made to achieve optimum results or minimize side effects.

According to the National Cancer Institute, the 5-year survival rates of people with sarcoma are:

  • 56% for localised sarcoma

  • 19% for regional sarcoma

  • 16% for metastatic sarcoma

It is important to note that despite successful treatment, patients are still at risk of recurrence. Sarcoma can develop again at the original site or other body parts. Thus, it is important that they undergo periodic follow-up exams even after a long period of remission.

References:

  • Longhi A, Errani C, De Paolis M, Mercuri M, Bacci G (Oct 2006). "Primary bone osteosarcoma in the pediatric age: state of the art". Cancer Treat Rev. 32 (6): 423–36. doi:10.1016/j.ctrv.2006.05.005. PMID 16860938.

  • Borden EC, Baker LH, Bell RS, et al. (Jun 2003). "Soft tissue sarcomas of adults: state of the translational science". Clin Cancer Res. 9 (6): 1941–56. PMID 12796356.

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