Biphasic mesothelioma is a mixture of epithelioid and sarcomatoid cells. For a tumor to be diagnosed as biphasic, each cell type must make up at least 10 percent of it. This is most common in pleural mesothelioma cases. A higher percentage of sarcomatoid cells indicates a more aggressive cancer.
Malignant biphasic mesothelioma is the second most common cell type of the disease. Patients with this form of cancer will have varying life expectancy rates because prognosis will depend on the ratio of epithelial and sarcomatoid cells. The larger the percentage of sarcomatoid cells the poorer the prognosis. Learning about biphasic and understanding its characteristics, how it is diagnosed, and how this type affects treatment can help you make informed decisions with your doctor.
Approximately 20 to 35 percent of all malignant mesothelioma cases are classified as biphasic. This cell type is more common among pleural patients. It is important to determine which cells are present because this information may have an impact on your prognosis.
In biphasic cases, epithelioid cells and sarcomatoid cells can exist in close proximity or, more frequently, within distinctly separate areas of a tumor. These cell types are important to detect because some clinical trials and treatments can be targeted at specific cell types. The characteristics of your cell type do not affect your symptoms and they may only affect your prognosis by a few months.
Epithelioid mesothelioma is comprised of round, cube-like cells that have long and slender microvilli, which are small hair-like protrusions in the cell membrane.
Biphasic mesothelioma is often called the “mixed” cell type because it is made up of cells from both of the other mesothelioma cell types.
Sarcomatoid mesothelioma is made up of spindle-shaped cells arranged in a disorganized fashion.
This type can be difficult to detect and diagnose because during a key diagnostic test called biopsy, doctors may collect only a small sample of tissue to study in the lab. Taking samples from just one location offers a limited view of the type and amount of mesothelioma cells involved.
Patient Advocate Karen Selby explains biphasic mesothelioma.
Doctors can make a more accurate diagnosis by taking tissue samples from several parts of the tumor. Determining the specific cell type is important to the diagnostic process because it can affect your treatment options and prognosis.
To distinguish biphasic mesothelioma from other diseases easily confused with this cancer, doctors use advanced tests like immunohistochemistry. This technique can detect certain proteins in cells, revealing the specific type of abnormal cells found with this diagnosis.
The diagnostic process can be harder for biphasic patients since epithelioid and sarcomatoid cells must both be detected.
With this information, doctors can rule out common misdiagnoses, including cancers like synovial sarcoma and carcinosarcoma.
A recent study published in the Journal of Thoracic Oncology found the biphasic type can be misdiagnosed after a biopsy. A total of 83 patients in the study were confirmed to have this type of pleural cancer after undergoing an extensive surgical procedure called an extrapleural pneumonectomy.
However, only 26 percent of those patients had been originally diagnosed with this subtype. The authors explained biphasic mesothelioma can be more accurately diagnosed following surgery. The initial diagnostic methods included thoracoscopy, thoracotomy, computerized tomography and other biopsy methods.
Treatment generally depends more on the stage and location of the tumor than the cell type involved. Because biphasic carries a slightly poorer prognosis than epithelioid, patients with the biphasic cell type may not be considered for an aggressive treatment plan as would epithelioid patients. However, treatment is not completely based on cell type, and most patients undergo one or more of the three most common therapies, including:
The prognosis for patients with this cell type will vary depending on the mix and ratio of epithelial and sarcomatoid cells that are present in each case.
The more epithelial cells you have in a biphasic mix, the better your prognosis may be. How much better may amount to only a few months depending on the case.
In one study involving 85 pleural mesothelioma patients with a variety of cellular subtypes, people with the biphasic subtype had an average survival of about 15 months. Those with the epithelial subtype displayed the highest average survival — more than 22 months.
The researchers observed slightly better survival among biphasic patients whose tumors had mostly epithelial cells, compared to those with mostly sarcomatoid cells. While the survival advantage was only 16 days, sarcomatoid cells are less responsive to treatment than epithelial cells. As a result, biphasic patients with a lower number of sarcomatoid cells tend to see better results from treatment.
Karen Selby joined Asbestos.com in 2009. She is a registered nurse with a background in oncology and thoracic surgery and was the director of a tissue bank before becoming a Patient Advocate at The Mesothelioma Center. Karen has assisted surgeons with thoracic surgeries such as lung resections, lung transplants, pneumonectomies, pleurectomies and wedge resections. She is also a member of the Academy of Oncology Nurse & Patient Navigators. Read More
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