Epithelioid mesothelioma is the most common mesothelioma cell type, accounting for roughly 70% of all cases. Epithelial cells grow at a relatively slow rate, causing them to respond favorably to treatments like surgery, chemotherapy, and radiation. For this reason, epithelioid mesothelioma has the best prognosis and survival rate of all cell types, with patients often surviving 1-2 years after their diagnosis.
What Is Epithelioid Mesothelioma?
Epithelioid (or epithelial) mesothelioma is one of the three cell types of the rare cancer malignant mesothelioma. The other two mesothelioma cell types are sarcomatoid and biphasic.
Healthy epithelial cells typically develop from a type of tissue that forms as wounds heal, called granuloma. When these cells are exposed to asbestos fibers, however, they can mutate and form mesothelioma tumors.
Malignant epithelioid mesothelioma cancer generally responds well to treatment. Patients with this cell type tend to live longer than patients with biphasic or sarcomatoid mesothelioma, provided that doctors can diagnose their cancer before it spreads.
Epithelial Mesothelioma Diagnosis
Doctors follow a multi-step process to diagnose epithelioid mesothelioma after a patient reports symptoms.
1. Physical Examination
Doctors will first perform a physical examination to help determine the cause of the symptoms.
If the patient has a history of asbestos exposure, or if the doctor suspects mesothelioma for any other reason, they will look for specific signs of this cancer. One common indicator of mesothelioma is fluid buildup in the lung lining (pleural effusions).
2. Imaging Tests
If physical examination suggests signs of disease, doctors will use imaging tests to look for tumors, scar tissue, or other telltale signs of mesothelioma. Imaging tests may include X-rays, magnetic resonance imaging (MRI) scans, or computed tomography scans (CT scans).
One of the most critical benefits of imaging tests is that they can provide information on whether there are tumors present as well as the potential location of the mesothelioma.
Imaging tests can not conclusively diagnose mesothelioma, so if radiologists or doctors see visible cancer signs, they will request a biopsy.
The only way to confirm a mesothelioma diagnosis is through a biopsy, in which a piece of a tumor is removed or fluid is collected. The pathologist takes a tissue or fluid sample of the affected area and examines it under a microscope to see if cancer cells are present.
Once a diagnosis is made, the doctor can determine if the malignant cells belong to an epithelioid cell subtype.
Diagnosing Epithelioid Mesothelioma Using Biomarkers
Specialists will also look for biomarkers, which help them to distinguish mesothelioma cells from cells of other, similar illnesses and avoid misdiagnosis. This technique is called immunohistochemistry staining.
According to the American Society of Clinical Oncology (ASCO), the diagnostic process for epithelioid mesothelioma should include immunohistochemistry staining. This allows doctors to look for certain proteins (such as calretinin) and other signs of mesothelioma cancer.
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Types of Mesothelioma Cells
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Epithelioid Mesothelioma Prognosis
Patients with epithelioid mesothelioma typically have a life expectancy of 1-2 years following their diagnosis.
Epithelioid mesothelioma generally has a better prognosis (expected outcome of a disease) than the other two cell subtypes — largely because epithelial cells spread fairly slowly. The table below details epithelioid patient survival compared to the other mesothelioma cell types.
Epithelioid Mesothelioma Treatment
Like all forms of this cancer, epithelioid mesothelioma is usually treated using a combination of surgery, chemotherapy, and radiation (multimodal treatment). Epithelial cells are more responsive to these mesothelioma treatments than the other cell types.
Removing tumors through surgery is the most effective way to treat epithelioid mesothelioma because it slows the spread of cancerous epithelial cells.
Patients with the epithelioid cell type are more likely to qualify for mesothelioma surgery when compared to patients with sarcomatoid cells or biphasic tumors, according to a 2012 study.
The most common surgeries for patients with epithelioid pleural mesothelioma are extrapleural pneumonectomy (EPP) and pleurectomy with decortication (P/D). Patients with epithelioid peritoneal mesothelioma may qualify for cytoreductive surgery with HIPEC.
Chemotherapy for epithelioid mesothelioma is administered intravenously to stop cancer cells from spreading. Patients will typically need multiple rounds of chemotherapy.
Common chemotherapy drugs for mesothelioma include pemetrexed, cisplatin, carboplatin, and gemcitabine.
Mesothelioma radiation therapy is administered by a machine that delivers high-energy wavelengths to the tumor site, which causes the epithelioid mesothelioma cells to die and the tumors to shrink.
Radiation may be used to supplement a surgery or as a main course of treatment if surgery is not an option.
Improving Prognosis With Treatment
Research has shown that multimodal treatment can improve the long-term survival rates of epithelioid mesothelioma patients.
According to a 2017 study, patients with epithelioid malignant pleural mesothelioma who received a combination of EPP surgery, chemotherapy, and radiation had a median survival time of about 23 months.
Patients with epithelioid mesothelioma may also access promising new treatment options through clinical trials, which test emerging treatments to hopefully improve survival rates and find a cure.
Rare Types of Epithelial Mesothelioma Cells
There are several subtypes of epithelioid mesothelioma, some of which are extremely rare and, in some cases, benign (non-cancerous).
Subtypes of epithelial mesothelioma include:
Adenoid cystic mesothelioma: Cystic cells are rare and not fully understood. They are often benign and don’t usually spread to distant sites.
Adenomatoid mesothelioma: Adenomatoid, also known as glandular epithelioid subtype, is very rare and generally originates within a patient’s genital glands. It accounts for roughly 6% of epithelioid pleural mesothelioma diagnoses.
Deciduoid mesothelioma: Deciduoid cells are characterized by their distinct borders and large oval shapes. This type of mesothelioma is associated with a very poor prognosis.
Papillary mesothelioma: This subtype is much more common in women than men and is slow to progress. It is also rarely linked to asbestos exposure, unlike almost all other types of mesothelioma.
Small-cell mesothelioma: This extremely rare subtype is often mistaken for other small-cell cancers.
These subtypes grow at different speeds and respond uniquely to treatments. For these reasons, identifying a patient’s epithelioid mesothelioma subtype allows oncologists to provide them with a more accurate prognosis.
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Hope for Victims of Epithelioid Mesothelioma
Epithelioid mesothelioma patients may find hope in knowing that this cell type typically responds well to treatments. That said, if you have been recently diagnosed with epithelioid mesothelioma, you may still have questions or concerns.
You may be wondering how to provide for your family while you seek medical treatment — but, thankfully, there are support options available.
Learn how we can help you navigate life after an epithelioid mesothelioma cancer diagnosis.