What is Epithelioid Mesothelioma?
Epithelium is one of the four basic types of tissue found in the human body. This abundant tissue is made up of epithelial cells that line organs and blood vessels in the chest and abdomen. Epithelial cells are responsible for moving liquids, minerals and other substances in and out of the body, helping fight off potential threats, and communicating temperature and other internal fluctuations with surrounding tissues and cells. When epithelial cells are exposed to asbestos, a group of fibrous minerals, they can genetically mutate into cancerous epithelioid cells—a cell type of mesothelioma.
The annual incidence of mesothelioma in the United States is estimated to be around 3,300 cases per year. Epithelioid cells are the most common cell type of mesothelioma in comparison to sarcomatoid and biphasic, accounting for around 50-70% of diagnosed cases. Diagnosing mesothelioma cell type is a critical step to knowing overall disease prognosis, as each cell type responds differently to treatment.
As epithelioid mesothelioma is the most commonly encountered cell type, cellular characteristics, behavior and viable treatment options have been more widely studied compared to sarcomatoid and biphasic—the other two mesothelioma cell types.
Epithelioid cell type has the most favorable prognosis, with doctors usually offering a large range of aggressive and effective treatment options.
When cancerous tissues—usually in the form of a mass or a tumour—are found, health professionals use a biopsy (a sample of the tumor) to better understand how the cells look and behave. Biopsy samples are viewed under a microscope and cellular characteristics and behaviors are observed to ensure an accurate diagnosis is reached.
When a mesothelioma diagnosis is suspected, mesothelioma specialists test specific cellular markers to differentiate cells from other cancerous cells, such as lung and ovarian cancer, with similar characteristics and behaviors. Determining cell type within a mesothelioma diagnosis is critical so doctors can make accurate recommendations on which treatment plans will lead to the best prognosis.
Each mesothelioma cell type behaves differently, causing differences between treatment plans and in overall prognosis. Epithelioid cells replicate quicker than sarcomatoid and biphasic cell types, which is actually a good thing. Rapid duplication causes a cell to lump together, building themselves up and limiting their ability to spread throughout the rest of the body. Epithelioid cells to spread to other parts of the body, but at a much slower rate than other mesothelioma cell types.
When viewed under a microscope, epithelial cell type is typically characterized by a cube-like, uniform appearance and a well-defined single nucleus (cellular DNA). The cube-like physical appearance of epithelioid cells has a direct effect on the cell types slow spreading nature. Scientific research has found various epithelioid cell subtypes, each with their own unique characteristics, which are mentioned in further detail below.
Treatments for Epithelioid Mesothelioma
As mesothelioma is a relatively new form of cancer, the treatment methods are constantly evolving and improving with research. Apart from a patient’s age and overall physical health, the two main factors that influence treatment options are tumor location and disease stage. Possible treatments are relatively similar across all cell types, but the level of aggression used to treat the tumor is determined by the mesothelial cell type.
There are three standard mesothelioma treatments, which can sometimes be combined to give patients individual treatment plans to achieve the best possible prognosis:
Surgery is the most effective way to treat mesothelioma, as removing tumors prevents epithelioid cells from moving to other parts of the body (metastasis).
Chemotherapy is an anti-cancer drug that stops epithelioid cells from multiplying and therefore spreading. Multiple rounds of chemotherapy may be needed to stop the cells from spreading.
Doctors may also use radiation therapy to disrupt the internal replication mechanisms within epithelioid cells. Radiation therapy is administered by a machine that delivers high-energy wavelengths to the tumor site, which causes the cells to die and tumor to shrink.
The most effective treatment plans for epithelioid mesothelioma often include multiple approaches and therapies. Patients diagnosed with epithelioid mesothelioma may be presented with aggressive treatment plans, as this cell type typically responds well to treatment. Research findings suggest that aggressive treatments have the potential to extend life by months or years.
Epithelioid Mesothelioma Has the Best Prognosis
Different factors determine patient life expectancy and survival rate. A patient’s individual traits like age, gender and overall health, along with the tumors location, stage of cancer development and cell type are all considered when predicting prognosis.
With an average survival rate of 1 to 2 years following diagnosis, patients with epithelioid mesothelioma tumors have the longest life expectancy.
Epithelioid mesothelioma has the best prognosis as this cell type spreads slowly and responds very well to treatment. Prognosis improves in cases that are detected at an early stage, and estimated life expectancy is longer in patients with mesothelioma tumors located in the abdomen, over the chest and heart.
Epithelioid Cell Subtypes
Epithelioid tumors can contain a wide range of epithelioid subtypes, each displaying unique characteristics and behaviors. Understanding the cell subtypes present within epithelioid tumors is important, as many of these subtypes have specific origins in the body. Some of them are extremely rare and, in some cases, benign (non-cancerous). Identifying cell type can give doctors confidence that an accurate diagnosis has been made and paint a well-informed picture of how an epithelioid tumor is likely to behave and respond to treatment.
Once the epithelioid subtype is confirmed doctors are able to provide patients with an individual treatment plan.
- Adenomatoid/Glandular: Adenomatoid, also known as glandular epithelioid subtype is very rare, and generally originates within patient’s genital glands.
- Cystic: Cystic cells are rare and not fully understood. They are often being and don’t usually spread to distant sites.
- Deciduoid: Deciduoid cells are characterized by their distinct borders and large oval shapes. This epithelioid cell type was originally found in patients who had not been in contact with asbestos, however recent studies have now linked the presence of deciduoid cells to asbestos exposure.
- Papillary/Well-Differentiated Papillary Mesothelioma: Similar to deciduoid cells, asbestos is not always linked to the development of papillary or well-differentiated papillary mesothelioma.
- Small Cell: The name of this epithelioid subtype points to their uniform but small nature. Small cells are not specific to mesothelioma as they are found in varying types of other cancer.
- Tubulopapillary: Tubulopapillary cells are one of the most common subtypes of epithelioid mesothelioma.
- Solid: Solid cells present in either well-differentiated or poorly differentiated cell forms that are arranged in sheets. Solid cells are another common subtype of epithelioid mesothelioma.
- Micropapillary: Micropapillary cells present as elongated structures with no fibers or conducting cells at their core.
It’s important for all patients to consider seeking a second opinion on their cell type diagnosis. Mesothelioma is a complex and rare cancer with many factors that cause it to be misdiagnosed. For more information on seeing a specialist and confirming your mesothelioma diagnosis, contact a Victim Advocate today.