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Epithelioid Mesothelioma

Of the three main mesothelioma cell types, epithelioid is the most common form of the disease.

Key Points

  • 1

    The epithelioid cell type accounts for around 70% of mesothelioma cases.

  • 2

    Epithelioid cells typically show local growth into surrounding tissue and organs.

  • 3

    Preferred treatment is often multimodal.

  • 4

    Average survival for epithelioid mesothelioma is 18 – 24 months.

There are three main cell types of mesothelioma cancer, including epithelial, sarcomatoid and biphasic. Epithelioid mesothelioma is the most common of the three, making up around 70% of all mesothelioma cases. Epithelial cells themselves are not cancerous, but rather mutate into a cancerous form. The mesothelium (membrane that lines different cavities in the body) are made up of epithelial cells, and when such mutations take place, mesothelioma of the epithelioid cell type develops.

When looking at the cause of epithelial mesothelioma, asbestos exposure is the only known cause, though there are a variety of risk factors that are emerging as possible contributors to development of the disease.

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Characteristics of Epithelial Cells

Cancerous cells are often differentiated based on how they grow and spread, along with their shape and size. Epithelial cells aren’t as fast-spreading as sarcomatoid cells with their uniform formations, but they are known to spread locally and to the lymph nodes.

In terms of location, epithelioid mesothelioma is most commonly pleural-based, located in the linings of the lung, but can also be found in the abdomen, genitals and other reproductive regions.

When looking at cell shape, epithelial cells stand apart with a well-defined nucleus that can be used as a determining factor in cell type during biopsies. Typically epithelioid mesothelioma cells are flat or cube-shaped, but when they become cancerous they can take a variety of shapes, depending on subtype.

Epithelial Mesothelioma Subtypes

Under epithelioid mesothelioma, there are several subtypes that vary based on cellular structure, location and symptoms. The subtype can affect side effects, treatment and prognosis for the mesothelioma patient.

Rare Subtypes of Epithelioid Mesothelioma
Adenomatoid Mesothelioma
  • Location: Gland-like structures, usually the genital glands
  • Cell pattern: Flat or cube-shaped with lace-like metastasis
  • Also known as glandular or microglandular mesothelioma
Cystic Mesothelioma
  • Location: Peritoneum or pelvic peritoneum (frequent), or other pelvic structures (less frequent)
  • Cell pattern: Flat or cube-shaped cells forming thin-walled, localized cysts with no metastasis
  • Also referred to as multicystic mesothelioma
Papillary Mesothelioma
  • Location: Peritoneum, tunica vaginalis or pleura
  • Cell pattern: Round or ovoid cells forming papillae and sheets with slow, microscopic metastasis
  • Also referred to as well-differentiated papillary mesothelioma (WDPM)
Deciduoid Mesothelioma
  • Location: Pleura, abdomen
  • Cell pattern: Large polygonal or ovoid cells forming nodulated tumors with distant metastasis
  • Poor prognosis of 5 – 6 months, on average

Small cell mesothelioma can be considered an additional subtype of mesothelioma, but it is typically diagnosed in biphasic tumors, which have a combination of both epithelial and sarcomatoid cells. In some cases,  multiple biopsies may be necessary to confirm a diagnosis. Physicians must carefully analyze cancer cells to understand the type of cancer that a patient has. In addition to being mistaken for other subtypes under the mesothelioma umbrella, these forms are commonly misdiagnosed as other diseases. A misdiagnosis can greatly hinder effective treatment and life expectancy.

Diagnosing Epithelioid Mesothelioma

A mesothelioma diagnosis can be extremely jarring. However, the sooner that the cancer is diagnosed, the better the treatment options and life expectancy for the patient. Misdiagnosis and a long latency period often prevent early detection, so whenever symptoms of mesothelioma are recognized, it’s crucial that the individual seek medical attention as soon as possible and consult with a mesothelioma specialist.

Symptoms of Epithelioid Mesothelioma

Symptoms of epithelioid mesothelioma can strongly differ. The epithelioid cell type is most often seen with malignant pleural mesothelioma, of which symptoms include chest pain, dyspnea (shortness of breath) and pleural effusion (fluid buildup around the lungs).

What Affects Mesothelioma Symptoms
  • Patient’s age: Elderly patients are often more susceptible to related health issues.
  • Overall health: Those with poor health may be more affected by symptoms.
  • Pre-existing conditions: Other diseases and conditions can worsen symptoms.
  • Cancer subtype: Aggressive cancers often lead to more extreme symptoms.
  • Tumor location: Origin location will determine what nearby tissues and organs are affected.
  • Staging: Symptoms tend to be more severe in the later stages of diagnosis.

Image Testing

Diagnosing epithelioid malignancy typically starts with imaging tests after physicians look at the patient’s symptoms, medical history and other health factors. Common imaging techniques used for a mesothelioma diagnosis include X-rays, CT scans, MRIs and PET scans.

Purpose of Image Tests During a Mesothelioma Diagnosis
  • Identify a tumorous growth
  • Pinpoint tumor location
  • See tumor size
  • Monitor metastasis or shrinking
  • For follow-up purposes to recognize recurrence

Biopsy Procedures

Continued research is showing promise for other ways to identify mesothelioma and associated risk factors. For example, biomarkers show much promise but cannot yet prove whether or not a patient has mesothelioma. Currently, the only way to definitively diagnose the malignancy is with a biopsy. Biopsies can take many different forms, including needle biopsies, camera-assisted biopsies and surgical biopsies.

Purpose of Biopsies During a Mesothelioma Diagnosis
  • Collect a sample of cancerous tissue for examination
  • Determine whether a tumor is benign or malignant
  • Confirm that the cancer is mesothelioma
  • Determine cell type
  • Determine nuclear grade (evaluating shape and size of cell nuclei)

In addition to providing physicians with answers in regards to what type of cancer the patient has, the information that biopsies provide strongly guides treatment plans and patient prognosis. Biopsies allow for histology and cytology opportunities, which dive into cell characteristics and help prevent misdiagnosis by separating cell type from other diseases and detect the type of mesothelioma that a patient has.

Treatment for Epithelioid Mesothelioma

Biopsies are one of the first steps in defining a general treatment plan. For example, if epithelioid malignant mesothelioma is caught in the early stages, surgery and chemotherapy are likely options for treatment. However, late-stage diagnoses might leave patients confined to palliative care, as they may be too weak to handle treatment side effects.

Common Mesothelioma Treatment Options

For epithelioid malignant mesothelioma, the most common treatment plan is a combination of surgery, chemotherapy and radiation, typically used together in a technique referred to as multimodal treatment. Since mesothelioma currently has no cure, the main goal is to eliminate or alleviate symptoms and provide the patient with the longest life expectancy possible.

Purpose of Traditional Treatments
  • Used curatively or palliatively
  • Targeted treatment
  • Meant to remove as much of the cancer as possible, or reduce pain and discomfort, such as by removing fluid buildup that can put pressure on affected organs
  • Used curatively or palliatively
  • Addresses mesothelioma cells throughout the body
  • Meant to destroy cancer cells and shrink tumors, alleviating associated symptoms
Radiation Therapy
  • Targeted treatment
  • Aims to kill cancer cells
  • Known to help with pain and shortness of breath

Along with helping alleviate cancer symptoms, treatments can cause their own set of side effects, especially chemotherapy. Physicians may determine that such a treatment option may not be viable for late-stage patients.

Palliative Care for Mesothelioma

A common misconception is that palliative care is only for patients that are nearing the end of their lives. However, palliative care is a great option for any patient, providing them with comfort through their treatment journey.

Palliative options vary greatly, ranging from surgery and chemotherapy to yoga and support groups. Patients should discuss with their healthcare provider to establish a palliative care plan that will best address personal symptoms and discomforts.

Prognosis for Epithelioid Mesothelioma

Prognosis vs. Life Expectancy

  • Prognosis offers a prediction of how the disease will develop
  • Life expectancy refers solely to the expected lifespan for the patient

As with diagnosis and treatment plans, prognosis varies from patient to patient and depends on a variety of factors. In terms of general prognosis, those that are undergoing multimodal care are likely to experience a better prognosis and longer life expectancy, compared to those that result solely to palliative treatments. Drug combination therapy has also positively impacted survival rates with pemetrexed and cisplatin showing much promise when used together.

Epithelioid Mesothelioma Life Expectancy

The median survival rate for those diagnosed with epithelioid mesothelioma is 18 – 24 months. Compared to sarcomatoid mesothelioma, treatment options have a much more positive impact on life expectancy, with 60% of epithelioid patents showing survival rates of over a year after receiving treatment. This is in part because the epithelioid type is much less aggressive than sarcomatoid and responds better to treatment.

Nuclear grading is used by many as a way to pinpoint life expectancy. Epithelial cells have a well-defined nucleus, making them an excellent contender for the grading system. For those with a nuclear grade of 1, the median patient survival is 28 months. Increased grades lead to lower survival rates, with grade 2 averaging to 14 months and grade 3 averaging 5 months.

Although life expectancy for all malignant mesothelioma types is bleak, research and emerging treatments continue to establish hope for improving the lives of those diagnosed and offering more options to extend survival rates and contribute towards finding a cure.