Patients with epithelioid mesothelioma account for 50 to 70 percent of all diagnosed cases of the disease. The good news: The epithelioid cell type responds better to treatment, provides the best prognosis and is the most preferred in mesothelioma clinical trials.
The cells within a mesothelioma cancer tumor can vary from patient to patient. If your tumor is mainly composed of epithelioid cells, you may respond better to treatment and experience a more favorable outcome than patients with other cell types.
Mesothelioma develops in the mesothelium, a lining made of epithelial cells. When epithelial cells of the mesothelium turn cancerous, they alter in appearance and take on patterns called epithelioid, sarcomatoid or biphasic. Epithelioid mesothelioma, which is also called epithelial mesothelioma, is the most common type of the asbestos-related disease.
Although treatment does not typically differ from one cell type to the next, your type may dictate which clinical trials are available to you.
Epithelioid cells cannot be identified with diagnostic imaging scans. To determine which cell type is present, doctors need to perform a thoracoscopy or similar form of surgical biopsy. Biopsies offer doctors a way to examine the potentially cancerous cells under a high-powered microscope. During a biopsy, a tissue sample of the tumor is extracted for further evaluation of the cells it contains.
Epithelioid mesothelioma accounts for the majority of cases.
One of the primary challenges of diagnosing epithelioid mesothelioma is distinguishing it from other types of cancer. Cancer in epithelial tissue could be a number of malignancies, which is why extensive testing is important. Epithelioid mesothelioma is often confused with adenocarcinoma, a common type of cancer that develops in the lungs, breasts and colon. Glandular mesothelioma, an epithelial cell subtype, may resemble adenocarcinoma of the lungs. It may be difficult to differentiate these two conditions.
Immunohistochemistry is a process that detects proteins called antibodies on the surface of cells. These proteins help classify a cancer’s cell type. Pathologists use immunohistochemistry to identify epithelioid mesothelioma cancer and differentiate it from adenocarcinoma. Immunohistochemistry is used less often to differentiate sarcomatoid mesothelioma from other sarcomatoid tumors.
Because epithelioid mesothelioma cells respond best to treatment, a patient with this type may be considered for a more aggressive treatment plan. Epithelioid patients diagnosed before the cancer has spread throughout the chest often qualify for multimodal therapy, which attempts to kill cancer cells with multiple therapies. Multimodal therapy combines the most effective anticancer treatments for mesothelioma, including surgery, chemotherapy and radiation therapy.
Your doctor’s pathology will show the specific cell type of your cancer. If you haven’t been told your cell type, be sure to ask your doctor and request a copy of the pathology report for your records.
In 1999, Dr. David Sugarbaker published impressive survival results among a group of pleural mesothelioma patients with malignant epithelial cells who had multimodal therapy that included an extrapleural pneumonectomy surgery, chemotherapy and radiation therapy. About 46 percent of patients who had epithelial cell type, no lymph node involvement and no remaining cancer cells after surgery lived at least five years. The typical five-year survival rate for mesothelioma cancer is around 10 percent.
Less than half of epithelioid patients qualify for aggressive surgery and multimodal therapy. And more than half are diagnosed too late to qualify for surgery regardless of cell type. When surgery isn’t an option, chemotherapy is considered standard of care and clinical trials are discussed.
Epithelioid patients have the widest variety of mesothelioma clinical trials to choose from. Most mesothelioma trials recruit epithelioid patients because their tumors respond best to treatment.
The best prognosis is associated with epithelioid cells. The median survival time with epithelioid mesothelioma is about one year after diagnosis. Comparatively, patients with sarcomatoid mesothelioma live an average of six months.
The improved prognosis is around 200 days on average, but it could amount to years if the cancer is diagnosed in an early stage.
In 1996, a now well-known Swedish study examined tumor cell type as a prognostic factor in 85 cases of pleural mesothelioma. Patients with epithelioid mesothelioma survived about 200 days longer than patients with sarcomatoid or biphasic cell types. Those with tubulopapillary cells, a subtype of epithelial mesothelioma, lived 275 days longer than patients with other cell types.
Overall, epithelioid mesothelioma is associated with better response to treatment and longer survival. This cell type can open a window for patients to access aggressive treatment plans and innovative clinical trials.
I believe with my heart that those that survive are warriors. I often joke with my friends that mesothelioma whispered in my ear, ‘You can’t handle me.’ And I told mesothelioma, ‘no, you can’t handle me.’
— Judy Goodson, peritoneal mesothelioma survivor diagnosed in 2013
Tumors are classified by the type and appearance of the cells involved. Epithelial cells form the epithelium, which is the most common of the four major tissue types in humans. With functions including protection, sensory perception and fluid secretion, epithelial tissue lines several major body cavities and most of our organs. Epithelial cells are also present in our skin, eyes, taste buds and ears.
The structure of epithelial tissue will vary depending on its location and function. Epithelial cells may appear thin and flat, and shaped like cubes, hexagons or columns. When the epithelial cells turn cancerous, they can take on several visual patterns: Epithelioid, sarcomatoid and biphasic. Usually they lose uniformity or otherwise become atypical in appearance, but they can also form small tubes or clusters that resemble a raspberry.
Because epithelioid cells lack mobility and adhere closely together, they are less likely to spread, as sarcomatoid cells do, to distant locations. Epithelioid cells primarily spread to nearby lymph nodes and from there migrate locally via the lymphatic system. Conversely, sarcomatoid cells are loosely organized, and they can migrate easily, leading to quicker metastasis.
Epithelioid cells are more common in cases of malignant pleural mesothelioma than peritoneal mesothelioma. A certain type of epithelioid mesothelioma occurs more commonly in women, and it’s known as well-differentiated papillary mesothelioma. No other cell type is associated with a particular gender, age or race.
Epithelioid mesothelioma has many subtypes, each with its own unique characteristics. Some subtypes are more likely to develop in specific parts of the body, while others are extremely rare. While the subtype you have won’t affect your treatment, it does help doctors tell mesothelioma apart from similar cancers.
The following are technical descriptions of some cell patterns doctors have observed in cases of epithelial mesothelioma.
The tubulopapillary cell pattern is one of the most common subtypes of epithelioid mesothelioma. Most tubulopapillary mesotheliomas contain well-differentiated cells. Doctors may mistake this subtype for adenocarcinoma that has spread to the pleura.
Adenomatoid mesothelioma, also known as the microglandular subtype, accounts for 6 percent of all pleural mesothelioma cases. These tumors are made of bland cells that are flat to cube-like in shape and lined by small gland-like structures.
They often appear alongside other subtypes but may also be the dominant cell pattern. It can be difficult for doctors to tell this subtype apart from other tumors, including benign adenomatoid tumors and metastatic adenocarcinoma of the pleura.
The solid subtype has two patterns: Well-differentiated and poorly differentiated.
Solid well-differentiated is one of the most common cell patterns seen in mesothelioma cancer. Its round cells form nests, cords or sheets. The poorly differentiated pattern has relatively unorganized cells that are polygonal to round in appearance.
Solid well-differentiated mesothelioma may be mistaken for benign reactive mesothelial hyperplasia, while the poorly-differentiated pattern appears similar to lymphoma and large cell carcinoma.
Tumors with the glandular pattern are mostly composed of acinar or gland-like structures. This subtype usually develops in the pleural lining. It may be confused for adenocarcinoma that has spread to the pleura.
Deciduoid mesothelioma is a rare epithelial subtype that may be caused by factors other than asbestos exposure. This pattern features large round to polygonal cells with sharp borders.
Because it is so uncommon, deciduoid mesothelioma can be mistaken for other conditions, including squamous cell carcinoma, anaplastic large cell lymphoma, gastrointestinal autonomic nerve tumor, pseudotumoral deciduosis, trophoblastic neoplasia and the oxyphilic variant of ovarian clear cell carcinoma.
A slow-growing variant that is not prone to spread, well-differentiated papillary mesothelioma features papillae lined by a single layer of flat mesothelial cells. This type usually affects young women and is not related to asbestos exposure.
Rebuilding and getting back to ‘normal’ isn’t a race for the swift. It’s for those who can endure the highs and lows. There are small victories and setbacks. But eventually, the battle is won.
— Kasie Coleman, peritoneal mesothelioma survivor diagnosed in 2010
There are things you can and cannot control when it comes to your prognosis. You cannot control the cell type of your cancer or how it will impact your life span. But there are other prognostic factors you can control such as the treatments you choose and lifestyle choices you make.
Participating in clinical trials, improving your diet and exercising regularly will boost your immune system. You can reach out to loved ones and join a support group. You can work with a palliative care specialist to manage symptoms and boost quality of life.
These are a few of the steps you can take to help you live longer with epithelioid mesothelioma cancer. Along with proper treatment and the help of a mesothelioma specialist, it is possible to outlive the average mesothelioma prognosis.
Joining the team in February 2008 as a writer and editor, Michelle Whitmer has translated medical jargon into patient-friendly information at Asbestos.com for more than eight years. Michelle is a registered yoga teacher, a member of the Academy of Integrative Health & Medicine, and was quoted by The New York Times on the risks of asbestos exposure.
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