Sarcomatoid mesothelioma accounts for approximately 15% of all mesothelioma diagnoses. It is the least common mesothelioma cell type and the most aggressive form of the disease.
What Is Sarcomatoid Mesothelioma?
Sarcomatoid mesothelioma is the rarest mesothelioma cancer cell type.
Like all mesothelioma, it is caused by exposure to asbestos fibers. Sarcomatoid mesothelioma is sometimes called spindle cell mesothelioma because tumor cells are oval or spindle-shaped. Sarcomatoid cells can metastasize to distant organs quickly and are difficult to treat.
The other two mesothelioma cell types are epithelioid and biphasic. Epithelioid is a distinct type of cell, while biphasic tumors contain a mixture of both epithelioid and sarcomatoid cells.
Tumors made up of sarcomatoid cells most often grow in the pleura (the lining of the lung) and are less common in the peritoneum (the lining of the abdomen).
Things to Know About Sarcomatoid Mesothelioma
Treatment exists: While patients with a sarcomatoid cell type tend to have a poorer prognosis, there are treatment options available, including promising results with immunotherapy.
Clinical trials may expand options: Patients can seek out clinical trials offering emerging therapies like immunotherapy, which can bring sarcomatoid survival rates closer to the same level as less aggressive forms of mesothelioma
Think about a second opinion: Every now and then, pathologists misdiagnose the severity of mesothelioma. And sometimes a second opinion reveals a better outcome than initially diagnosed.
Sarcomatoid Characteristics and Subtypes
There are a few common characteristics of sarcomatoid cells:
- Sarcomatoid cells are long and are shaped like spindles or ovals.
- Sarcomatoid cells grow in a haphazard pattern, which allows them to spread faster than other mesothelioma cell types.
- How sarcomatoid cells spread makes them more resistant to treatment, contributing to a poorer prognosis.
Desmoplastic sarcomatoid cells are long and tend to look like bundles of collagen, a healthy protein found in the bones, muscle, tendons, and skin. At least half of a desmoplastic tumor will appear patternless, making it difficult to diagnose. Desmoplastic sarcomatoid cells account for about 5% of all mesothelioma diagnoses.
Lymphohistiocytoid cells are large and shaped like spindles. They usually appear together with immune and inflammatory cells. The lymphohistiocytoid subtype accounts for less than one percent of all mesothelioma diagnoses.
Transitional sarcomatoid cells are plump and shaped like spindles.
These tumors are exceedingly rare and can be difficult to diagnose because transitional sarcomatoid cells can resemble epithelioid cells. However, they tend to grow in similar ways to other sarcomatoid subtypes.
How Sarcomatoid Mesothelioma Symptoms Develop
Sarcomatoid mesothelioma symptoms can take 10-50 years to develop, given a decades-long latency period between asbestos exposures and cancer development. Since sarcomatoid cells usually indicate pleural mesothelioma (cancer in the lining of the lungs), symptoms often include shortness of breath and chest pain as cancer spreads into the soft tissue of the chest wall.
Sarcomatoid tumor cells are generally not found in peritoneal mesothelioma, which occurs in the abdomen.
Common sarcomatoid mesothelioma symptoms
- Chest pain or pressure
- Persistent cough (usually dry)
- Shortness of breath
- Fatigue or weakness
- Loss of appetite
- Weight loss
Sarcomatoid Mesothelioma Diagnosis
Even specialists find it difficult to diagnose sarcomatoid cells due to their similarity to other cancer cells. Sarcomatoid tend to look like the benign tissue cells surrounding the tumor and sarcomas, a form of cancer that occurs in bone, muscle, or cartilage cells.
Sarcomatoid type mesothelioma is commonly misdiagnosed as:
- Sarcomatoid carcinoma
- Various sarcomas, such as synovial sarcoma, a cancer occurring near the arm, leg, or neck joints.
- Fibrous pleurisy
- Fibrous histiocytoma
Diagnosing Through Immunohistochemistry and Biopsy
A pathologist is a doctor who specializes in identifying cells to confirm a diagnosis. Pathologists use a technique called immunohistochemistry to apply special stains to samples taken from a biopsy. This technique helps them differentiate sarcomatoid cells from cells belonging to other cancers.
The stains they use contain markers, often proteins, that are attracted to certain cells. These markers attach themselves to cells, making them easier to see under a microscope. Pathologists can also identify sarcomatoid cells under a microscope by the absence of epithelial, or tissue, elements within the cell.
Markers for which sarcomatoid mesothelioma tests positive include:
- Cytokeratin: A protein found in epithelial tissue. Sarcomatoid mesothelioma cells usually contain cytokeratin, while most sarcomas do not.
- Podoplanin (D2-40): Through proposed by researchers as a positive marker, more studies must be completed to confirm its usefulness.
Mesothelioma diagnosis generally begins with an X-ray and CT scan, which will indicate cancerous growths. Patients may undergo multiple biopsies to determine if their mesothelioma tumors are made up entirely of sarcomatoid cells. Tumors with both sarcomatoid and epithelioid cells are called biphasic.
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Sarcomatoid Mesothelioma Treatment Options
Sarcomatoid cell types are more resistant to treatment due to their haphazard spread pattern, rigidity, and aggressive metastasis (spread) to other parts of the body.
Surgery is most effective on patients with early stage sarcomatoid mesothelioma because at this stage, the tumor has not yet spread to other parts of the body.
Removing advanced-stage pleural sarcomatoid tumors can be difficult. Sarcomatoid cells tend to spread into the chest wall, making surgery challenging at later stages.
Sarcomatoid tumors in the abdomen are also difficult to remove due to their proximity to the soft organs in the abdominal area.
Chemotherapy alone has not yet proven itself as an effective treatment for sarcomatoid type mesothelioma.
Radiation therapy may sometimes be used to treat sarcomatoid mesothelioma, especially if cancer is found at an early stage. It may also be used as a palliative treatment to shrink tumors and improve quality of life.
Studies have shown that select drugs have produced positive results when used to treat patients with sarcomatoid mesothelioma:
- Selenite: This mineral has been shown to inhibit the growth of sarcomatoid cells.
- Selenite with doxorubicin: Selenite amplifies the effect doxorubicin has on epithelioid cells. The combination of both drugs induced cell death (apoptosis) in the majority of treated cells.
- Cyclophosphamide, vincristine, adriamycin, and dacarbazine (CYVADIC): This chemotherapeutic treatment is a combination of four drugs, and has proven successful in treating soft cell cancers in a variety of clinical trials.
Sarcomatoid mesothelioma is not curable. However, emerging treatments offer hope to patients. They can also provide improved quality of life through palliative care. Some therapies are still in clinical trials while others have received FDA approval. The effectiveness of these treatments varies based on the histology of the tumor.
These treatments include:
- Tumor Treating Fields
A landmark clinical study called Checkmate 743 compared immunotherapy with chemotherapy in treating pleural mesothelioma. With immunotherapy, patients with sarcomatoid pleural mesothelioma could achieve a three year survival rate similar to that of patients who had tumors that only contain epithelioid cells. Immunotherapy is used to stimulate the immune system to fight cancer on its own. In particular, the combination of two immunotherapy drugs, Opdivo® (nivolumab) and Yervoy® (ipilimumab) have been shown to improve survival rates by 50%. These two drugs are an FDA-approved treatment for malignant pleural mesothelioma, and work together to identify and target cancer cells in the body. These treatments are now standard options for advanced stages of mesothelioma, as well as for mesothelioma that involves sarcomatoid cells.
Tumor Treating Fields are electrical fields that pulse through the skin and interrupt how cancer cells divide. This non-invasive treatment, which has been approved by the FDA, is now standard treatment in conjunction with chemotherapy. Some patients have lived up to six months longer with the addition of Tumor Treating Fields in their treatment plan.
ADI-PEG-20 is a drug that blocks cancer cells from getting arginine—an essential element for growth. Used in conjunction with chemotherapy, ADI-PEG-20 has shown promise in limiting the growth of tumors.
Sarcomatoid Mesothelioma Prognosis, Survival Rates, and Life Expectancy
Patients diagnosed with sarcomatoid mesothelioma have a less favorable prognosis than patients with epithelioid or biphasic (partial sarcomatoid) mesothelioma. The median survival rate for a sarcomatoid mesothelioma patient is 6 months after diagnosis. However, there is hope for patients with sarcomatoid mesothelioma.
Prognosis is affected by the stage of disease, age, gender, and overall health of the patient when diagnosed. Life expectancy increases if cancer is found in earlier stages. Younger patients, female patients, and patients in good overall health tend to have a longer life expectancy.
Treatment also plays an important role in increasing life expectancy. Patients should speak with their doctors about treatment options, including clinical trials and emerging therapies, that can help extend life. Immunotherapy in particular can raise sarcomatoid survival rates to be more similar to those of epithelioid mesothelioma patients.
Mesothelioma treatments continue to improve in both number and results; talk to a specialist to learn more about treatment options that can give you a better prognosis.
Sarcomatoid Mesothelioma FAQs
Is sarcomatoid a specific type of mesothelioma?
Yes; sarcomatoid mesothelioma describes a type of malignant mesothelioma where tumors are made up of sarcomatoid cells. Less than 20% of mesothelioma cases are sarcomatoid and it is more likely to occur in the lining of the lungs than any other place in the body.
What is the life expectancy of a person with sarcomatoid mesothelioma?
Patients diagnosed with sarcomatoid mesothelioma have a life expectancy of about six months.
What is spindle cell mesothelioma?
Spindle cell mesothelioma is another term for sarcomatoid mesothelioma. These tumors are made up of spindle-shaped sarcomatoid cells.
How do I get help with a sarcomatoid mesothelioma diagnosis?
To learn more about mesothelioma or to find information on cancer treatment, contact Mesothelioma Group at (800) 333-8975.
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Lonardo, F. Sarcomatoid mesothelioma and its histological mimics: a comparative immunohistochemical study. Histopathology, 270-279. Retrieved July 7, 2014, from http://www.ncbi.nlm.nih.gov/pubmed/12605647
Dobra, K. Selenite induces apoptosis in sarcomatoid malignant mesothelioma cells through oxidative stress. Free Radical Biology and Medicine, 874-885. Retrieved July 7, 2014, from http://www.sciencedirect.com/science/article/pii/S0891584906003534