What Is Soft Tissue Sarcoma? How Does It Differ from Other Cancers?

What Is Sarcoma?

Sarcomas are rare cancers that develop from connective tissue cells forming the framework of tissues such as bone and muscle. These tumors tend to grow rapidly and metastasize (spread) at early stages.

What Is the Difference Between Carcinoma and Sarcoma?

Carcinomas and sarcomas are the two main types of cancer. Carcinomas are cancers developing in epithelial cells lining internal organs and the outer surface of the body, such as lung, breast, colon and prostate cancers. Sarcomas are cancers developing in mesenchymal cells that form both bones and soft tissues such as muscles, tendons and blood vessels. Mesenchymal cells form what we call connective / supporting tissues.

Cancer occurs when accumulated genetic damage at the cellular level causes cells to divide uncontrollably and spread to other tissues (see what is cancer). This forms masses called tumors. Tumors that become cancerous are called malignant. Most cancer cases involve either carcinoma or sarcoma. Other main types of cancer are:

• Lymphomas: They affect cells in the lymph nodes.
• Myelomas: They affect plasma cells in the bone marrow.
• Leukemias: They affect bone marrow cells.

Which Parts of the Body Do Carcinomas and Sarcomas Affect?

The main difference between carcinomas and sarcomas is the cell from which they originate.

Carcinomas

Carcinomas originating from epithelial cells tend to affect the skin and mucous membranes.

The five most common types of carcinoma are:

• Adenocarcinoma: They affect organs producing fluid or mucus, such as the breast and prostate.
• Basal cell carcinoma: It affects cells forming the base of the outermost skin layer. This is the most common type of skin cancer.
• Squamous cell carcinoma: It affects cells above the basal cells of the skin and is the second most common type of skin cancer.
• Transitional cell carcinoma: It affects transitional cells in the urinary tract, including the bladder, kidneys and ureter.

You may be interested: Turkey Cancer Statistics 2020

Sarcomas

Sarcomas are tumors developing from soft tissue cells called mesenchymal cells. Mesenchymal cells help form and support many vital tissues and organs:

• Bones
• Blood vessels
• Cartilage
• Nerves
• Muscles
• Fat
• Joints
• Tendons
• Connective tissues

Sarcomas, compared with carcinomas, are much rarer; however, there are more than 75 types of sarcoma. They can occur anywhere, but are most common in the abdomen, arms and legs.

The most common types of sarcoma are:

Undifferentiated pleomorphic sarcoma: It involves both soft tissue and bone cells at the same time.

• Leiomyosarcoma: It involves smooth muscle cells lining blood vessels, the gastrointestinal tract and the uterus.
• Osteosarcoma: It involves bone cells.
• Liposarcoma: It involves fat cells.

How Common Are Carcinomas and Sarcomas?

Another difference between carcinomas and sarcomas is how common they are. Carcinomas are very common, whereas sarcoma is rarer.

How Common Are Carcinomas?

Approximately 90% of cancer cases originate from a carcinoma. Carcinomas can affect both sexes and people of all ages and ethnic backgrounds.

Different carcinomas have different risk factors / causes. Some include:

• Smoking
• Excessive alcohol consumption
• Prolonged exposure to ultraviolet rays from the sun
• Prolonged exposure to severe air pollution
• Obesity
• Inactivity or lack of physical activity
• Having fair skin
• Various infections (HPV, EBV, HBV, HCV, Helikobakter pilori, etc.)

How Common Are Sarcomas?

Sarcomas, among the cancers diagnosed each year, account for less than 1 percent. Like carcinomas, sarcomas can affect anyone. However, certain medical conditions, environmental influences and lifestyle habits can increase the risk of developing a type of sarcoma.

Medical risk factors / causes for sarcomas:

• Tubular sclerosis (Bourneville disease)
• Retinoblastoma
• Neurofibromatosis type 1 (Von Recklinghausen disease)
• Familial adenomatous polyposis (Gardner syndrome)
• Nevoid basal cell carcinoma syndrome (Gorlin syndrome)
• Werner syndrome
• Li-Fraumeni syndrome

Environmental and lifestyle factors for sarcomas:

• Exposure to harmful and toxic chemicals, particularly arsenic, thorium dioxide and vinyl chloride
• Exposure to radiation during cancer treatment
• Continuous and frequent exposure to repeated radiation from diagnostic imaging methods such as X-rays

In addition, some types of sarcoma are more common in particular age groups. Types more common in babies, children and young people include:

• Rhabdomyosarcoma
• Osteosarcoma
• Alveolar soft part sarcoma
• Desmoplastic small round cell tumor
• Epithelioid sarcoma
• Synovial sarcoma
• Infantile fibrosarcoma

Sarcomas more common in adults:

• Adult fibrosarcoma
• Fibromyxoid sarfkom, low grade
• Liposarcomas
• Myxofibrosarcomas, low grade

Which Are More Dangerous: Carcinomas or Sarcomas?

It is very difficult to say whether carcinomas or sarcomas are more dangerous. Survival rates for any type of cancer depend on various factors, including:

• Tumor size
• Tumor location
• Growth rate of the tumor or cancer cells
• Whether the cancer has spread to other tissues and organs (stage)
• How many times the cancer has recurred after treatment
• Overall health
• Age
• Additional medical conditions
• Sex
• Ethnicity

Why Is Immunotherapy Not Effective in Sarcoma?

Immunotherapy is a treatment aiming to destroy cancer cells using the body's own system. However, because sarcomas have a different structure from other cancer types, immunotherapy is often not effective. Sarcoma cells are also difficult for the immune system to recognize and target. For these reasons, immunotherapy may not work in sarcoma.

However, as a new development, in December 2022 the immunotherapy atezolizumab received FDA (US Food and Drug Administration) approval for treating alveolar soft part sarcoma, a rare soft tissue cancer (see the relevant approval).

Conclusion

Carcinomas and sarcomas are the two main types of cancer. Although they sound similar, they affect different parts of the body. Carcinomas are the most common cancer type, whereas sarcomas are relatively rare and originate from mesenchymal cells forming soft / connective tissue.