Epithelioid mesothelioma is the most common cell type of mesothelioma cancer.
The epithelioid cell type spreads slower than other mesothelioma cell types.
Survival for epithelioid mesothelioma, with treatment, is generally 18 months or more.
Multimodal treatment typically leads to the most favorable outcomes.
There are three main cell types of mesothelioma cancer:
The epithelioid cell type accounts for 70% of all mesothelioma cases. This makes it the most common of the three cell types. This type of mesothelioma arises when healthy epithelial cells mutate, becoming cancerous.
What Causes Epithelioid Mesothelioma?
Asbestos is the only known cause of all forms of mesothelioma. People can inhale or ingest airborne asbestos fibers. Once inside the body, these fibers cannot be broken down or cleared. Asbestos fibers can then cause irritation and inflammation around epithelial cells. Over time, this can lead to mesothelioma.
Healthy epithelial cells occur throughout the human body, including the mesothelium. The mesothelium is a membrane that lines various body cavities, such as the chest and abdominal cavities. When epithelial cells in the mesothelium become cancerous, epithelioid mesothelioma develops.
Asbestos exposure is the only known cause of all mesothelioma cell types. However, research shows several risk factors may contribute to development of the disease.
Characteristics of Epithelial Cells
Cancer cells are classified based upon a number of factors, including:
- The cell shape
- The cell size
- How fast they grow or spread
- Markers on the surface of the cell
Epithelial cancer cells are fairly uniform in shape. They have a well-defined cell center (nucleus). Pathologists may use this characteristic to identify them in biopsy samples. Healthy epithelial cells are flat or cube-shaped. Epithelioid mesothelioma cells may adopt a new shape once they become cancerous.
Epithelioid mesothelioma cells spread more slowly than sarcomatoid cancer cells. However, epithelioid mesothelioma cells may spread to nearby tissues, including lymph nodes.
Epithelial Mesothelioma Subtypes
There are several subtypes of epithelioid mesothelioma. They vary by cell shape, cancer location and symptoms. These properties can affect treatment options, side effects and prognosis for mesothelioma patients.
Rare Subtypes of Epithelioid Mesothelioma
- Location: Gland-like structures, usually the genital glands
- Cell pattern: Flat or cube-shaped with lace-like structures
- Also known as glandular or microglandular mesothelioma
- Location: Peritoneum (lining of the abdomen) or pelvic peritoneum (lining of the pelvis), or other pelvic structures
- Cell pattern: Flat or cube-shaped cells forming thin-walled, localized cysts with no metastasis
- Also referred to as multicystic mesothelioma
- Location: Peritoneum (lining of the abdomen), tunica vaginalis (lining of the testes) or pleura (lining of the lungs)
- Cell pattern: Round or oval cells forming papillae and sheets with slow, microscopic metastasis
- Also referred to as well-differentiated papillary mesothelioma (WDPM)
- Location: Pleura (lining of the lungs) and peritoneum (lining of the abdomen)
- Cell pattern: Large polygon or oval cells forming nodulated tumors with distant metastasis
- Survival times range from two to more than 38 months, depending on individual factors
Small cell mesothelioma is an additional subtype of mesothelioma. But, this subtype is usually found in biphasic tumors. Biphasic tumors have a combination of both epithelial and sarcomatoid cells.
Symptoms of Epithelioid Mesothelioma
Epithelioid mesothelioma may develop in the lining of the lungs, abdomen, heart or genitals. Mesothelioma symptoms vary based upon where it develops. Symptoms are also affected by patient age, overall health and the stage at diagnosis.
The Importance of Recognizing Symptoms
Unfortunately, early diagnosis of mesothelioma is difficult. The cancer takes many years to develop and causes generic symptoms.
Individuals exposed to asbestos fibers should know and recognize mesothelioma symptoms. If symptoms occur, the individual should seek medical attention as soon as possible. Symptoms and past asbestos exposure should be reported to a physician.
Diagnosing Epithelioid Mesothelioma
Diagnosis of epithelioid mesothelioma begins with imaging tests. These may include CT scans, PET scans, MRIs or X-rays. If these tests find abnormal tissue, the patient may have a blood test or biopsy. Blood tests may identify biomarkers that help determine the most effective treatment.
Currently, the only way to definitively diagnose epithelioid mesothelioma is with a biopsy. Biopsies can take many different forms. These include needle biopsies, camera-assisted biopsies and surgical biopsies.
- Collect a sample of cancerous tissue for examination
- Determine whether a tumor is benign or malignant
- Confirm the cancer is mesothelioma
- Determine cell type
- Determine nuclear grade (evaluating the shape and size of cell nuclei)
A biopsy sample can be analyzed for histology and/or cytology. These tests provide information about cell characteristics. They also help prevent misdiagnosis by ruling out other diseases.
Histology analysis is sometimes called immunohistochemistry. This long name means clinicians use antibodies to test the biopsy sample. Calretinin, D2-40 and WT1 antibodies are used together to identify epithelioid mesothelioma.
Physicians can use the information from a biopsy to help determine the best treatment plan.
Treatment for Epithelioid Mesothelioma
When epithelioid malignant mesothelioma is caught early, patients generally have more treatment options. These options include chemotherapy, surgery, immunotherapy and radiation. Research shows a combination of these options usually results in the most favorable life expectancy. Combination treatment is referred to as multimodal treatment.
Regrettably, when epithelioid mesothelioma is caught in a later stage, patients may have fewer options. In such cases, the individual may be too weak to handle the side effects of robust treatment. Therefore, they may be limited to palliative care options.
Common Treatment Options for Epithelioid Mesothelioma
- Used therapeutically or palliatively
- Addresses mesothelioma cells throughout the body
- Meant to destroy cancer cells and shrink tumors
- Examples: pemetrexed and cisplatin
- Used therapeutically or palliatively
- Aims to kill cancer cells
- Known to help with pain and shortness of breath
- Example: locally targeted radiation
These treatments aim to slow or stop cancer growth and symptoms. However, treatments can cause their own side effects. Mesothelioma physicians will keep this in mind when choosing the best treatment plan for each individual patient.
Palliative Care for Mesothelioma
Some people believe palliative care is only for patients nearing the end of their lives. This is a common misconception. Palliative care is an option for any patient. It can provide them with comfort throughout their treatment journey.
Palliative options vary greatly, ranging from surgery and chemotherapy to yoga and support groups. Patients should discuss these options with their healthcare provider. Together, they can establish a palliative care plan tailored to the individual.
Prognosis for Epithelioid Mesothelioma
Prognosis varies from patient to patient and depends on a variety of factors. In general, patients receiving multimodal care experience a more favorable prognosis and life expectancy. However, researchers continue improving upon existing treatments and creating new technologies every day.
Epithelioid Mesothelioma Life Expectancy
The median survival rate for those diagnosed with epithelioid mesothelioma is 18 months. This means half of all epithelioid patients live longer than 18 months. This may be due to the less aggressive nature of epithelioid mesothelioma versus other cell types. Epithelioid mesothelioma also responds better to treatment.
Life expectancy for all malignant mesothelioma types may seem bleak. But, clinical trials and emerging treatments continue to establish hope for mesothelioma patients. Multiple studies now report patients surviving for 10 years or more after diagnosis and treatment.