Sarcomatoid is the rarest and most aggressive of the three cell types used to differentiate and treat cases of mesothelioma. Sarcomatoid cell type is difficult to treat as the cells do not form masses like epithelioid and biphasic cell types and generally spread easily throughout the body.
Sarcomatoid Cell Type Overview
Knowing a patient’s cell type is important for doctors when determining treatment plans and overall prognosis.
If you’ve been diagnosed with sarcomatoid cell type, here’s what you need to know:
- Sarcomatoid is the least common cell type of mesothelioma
- Sarcomatoid cells are spindle-shaped and sometimes have multiple nuclei
- They organize as nodules, increasing their ability to spread through the body
- Sarcomatoid cell type does not respond well to treatment and has the least favourable prognosis
- Possible treatment plans for epithelioid cell type include surgery, chemotherapy and radiation therapy
What is Sarcomatoid Cell Type?
Each case of mesothelioma can contain different cell types with varying physical characteristics and growth behaviours, which have an affect on viable treatment options and a patients overall prognosis. Of the three cell types, sarcomatoid cells are the rarest and most challenging to treat, making up around 10% of all diagnosed cases of mesothelioma.
Sarcomatoid cells develop from mutations that occur during epithelial-to-mesenchymal transition (EMT), a normal process that transforms epithelial cells to mesenchymal cells, which make up our connective tissues. Sarcomatoid cell type is characterized by their spindle shape (more or less round in the middle with two ends that are pointed), large size and aggressive nature.
Due to their rarity, scientists have not been able to perform extensive studies on sarcomatoid cell type and cases are frequently misdiagnosed as healthy tissues, benign (non-cancerous) presentations or other types of cancer.
Patients diagnosed with sarcomatoid type generally have the least favourable prognosis and less treatment options when compared to the other two mesothelioma cell types—epithelioid and biphasic. Cell type along with along with tumor location and disease stage are important factors in determining a patient’s overall diagnosis. The three cell types found in mesothelioma respond differently to treatment and are critical considerations for doctors to develop the right treatment plan.
Sarcomatoid Cell Type Characteristics
Medical professionals perform a biopsy to collect tissue samples when a patient presents symptoms that are commonly experienced in varying forms of cancer. The tissue sample taken from the tumor mass (lump of potentially cancerous tissue) is viewed under a microscope to observe the cells characteristics to ensure an accurate diagnosis is made.
Sarcomatoid tissue samples are often difficult to diagnose as the cell type shares similar characteristics with cancers found in connective tissues (sarcomas), benign tissues found in the chest and other healthy tissues found in the body. For this reason, multiple screening tests need to be performed to ensure an accurate sarcomatoid mesothelioma diagnosis is reached and proper treatment plans are administered.
When viewed under a microscope, sarcomatoid cells appear irregular and spindle-shaped. These large cells generally organize into fibrous-looking groups, and in certain cases, sarcomatoid cells may contain more than one nucleus (cellular DNA). Subtypes of sarcomatoid have been identified and can be further classified with varying characteristics
Sarcomatoid Cell Type Behavior
Epithelioid, sarcomatoid and biphasic cells types display different cellular behaviors, which play a large factor in how mesothelioma grows and the rate at which it spreads. For this reason, cell type behaviour contributes to patient life expectancy and survival rates.
Unlike other cell types, sarcomatoid cells rarely present as organized masses. Sarcomatoid cells generally form as small nodules or lumps that scatter the lining or an organ or cavity in the chest or abdomen. As these small tumours grow they combine to form sheets of cancerous cells, making it very difficult for surgeons to scrape them out. This behavior allows sarcomatoid cells to spread very quickly throughout the body and results in a less favorable prognosis when compared to other cell types.
When observing an sarcomatoid mesothelioma sample under a microscope, it is possible to identify more than one sarcomatoid subtype, along with small amounts of epithelioid cells.
In recent studies, scientists that found that differences in subtypes have a large impact on patient prognosis.
The identification of a sarcomatoid subtype can also provide doctors with more clues to correctly diagnose sarcomatoid mesothelioma, as many of these subtypes originate in specific parts of the body and have characteristics that are extremely rare.
- Desmoplastic: Desmoplastic cells are one of the most common sarcomatoid subtypes and are commonly misdiagnosed.
- Osteosarcomatous: Osteosarcomatous cells are cancerous bone cells that are found in the mesothelium—the membrane that lines the chest, heart and abdominal cavities.
- Chondrosarcomatous: This sarcomatoid cell type is similar to Osteosarcomatous cells and is distinguished by cancerous cartilage in the mesothelium.
- Lymphohistiocytoid: Sarcomatoid cells within the lymphohistiocytoid subtype contain small amounts of epithelioid cells and are typically found bundled in the immune system.
Sarcomatoid Cell Type Prognosis
Prognosis is the term used to describe the likely disease course following diagnosis. These evaluations are based on the usual progression of a disease and can be different based on various factors. Prognosis is based on a combination of elements, such as, the patient’s age, gender and overall health, along with tumour location, cancer stage and in the case of mesothelioma, cell type.
Sarcomatoid mesothelioma has the least favourable prognosis in comparison to epithelioid and biphasic cell types. In a study that investigated 326 cases of sarcomatoid mesothelioma in 2010, most tumors were in the chest cavity (98%) with only 7 cases located in the abdomen. Median survival rate was 3.5 months. Other studies found similar poor prognoses, with a median survival of 6 months in one study, 5.8 months in another, and 6.2 months survival for desmoplastic sarcomatoid subtype.
In general, sarcomatoid mesothelioma is an aggressive subtype that does not respond well to treatment, but doctors will develop individual treatment plans for patients to ensure the best possible prognosis is achieved for their mesothelioma location, stage and cell type.
Treatments for Sarcomatoid Mesothelioma
As with other mesothelioma cell types, a patient’s treatment plan is heavily influenced by the location of their tumor and the stage of their disease. Other factors that can impact the types of treatment a patient will receive may include their age, previous response to medical treatments and overall health.
Sarcomatoid mesothelioma is the most difficult cell type to treat, especially if diagnosed in its later stages, because it does not typically grow as a single tumor mass and spreads throughout the body as a rapid rate. This growth behavior makes it very hard to get rid of the cancer completely with surgery and extremely difficult to treat with radiation therapy as sarcomatoid cell nodules are small, which makes them hard to accurately treat with high-energy particles of waves. Chemotherapy is an anti-cancer drug that prevents cells from replicating and spreading and has had some successes in treating sarcomatoid cell type, however multiple rounds may be needed.
Generally, doctors will create multimodal treatment plans that include surgery, chemotherapy and radiation to achieve the best possible prognosis for patients diagnosed with sarcomatoid cell type.
For more information on getting an accurate mesothelioma cell type diagnosis, contact out Patient Advocates today.