Biphasic Mesothelioma

Biphasic mesothelioma, also known as mixed mesothelioma, is one of three major cell types, alongside epithelioid and sarcomatoid. Biphasic is the second most common type comprising 20% – 40% of all mesothelioma cases.

Key Points

  • 1

    Biphasic mesothelioma tumors contain both epithelioid and sarcomatoid cells.

  • 2

    Misdiagnosis is common as a biopsy may not reveal both cell types.

  • 3

    Available treatments and prognosis vary according to dominant cell type.

  • 4

    Median survival generally ranges from 10 – 15 months after diagnosis.

Biphasic mesothelioma, also known as mixed mesothelioma, is one of the three major cell types. The biphasic tumor contains a mixture of epithelioid and sarcomatoid malignant cells, the other two major mesothelioma cell types. Prognosis and treatment options for biphasic mesothelioma vary depending on which cell type is most dominant.

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Biphasic Mesothelioma Cell Characteristics

The defining characteristic of biphasic tumors is the combination of both epithelioid and sarcomatoid malignant cells. The epithelioid and sarcomatoid cells sometimes group closely together within the tumor, but are more likely spread out, complicating biopsy samples and an accurate diagnosis.

The ratio of each cell type may vary, affecting the range and intensity of symptoms that cancer patients experience, growth characteristics and cancer behavior. However, there are a variety of other influencing factors that could challenge common cell type characteristics.

How Dominant Cell Type Commonly Influence Cancer Development
Epithelial Dominance
  • Local metastasis
  • Common symptoms, such as shortness of breath, chest pain, fever or night sweats, tightness in the chest and unexplained weight loss.
  • Longer life expectancy
  • Easier to treat
Sarcomatoid Dominance
  • Local and distant metastasis
  • Pain, breathing restrictions and symptoms related to metastasis, in addition to common symptoms
  • Shorter life expectancy
  • Harder to treat

Diagnosis of Biphasic Mesothelioma

Since mesothelioma is a rare form of cancer, it is often misdiagnosed as other diseases. To ensure an accurate diagnosis, physicians will note any reported smyptoms and perform a variety of tests to not only pinpoint the cancer, but provide the most effective treatment plan for the patient.

Common Symptoms of Biphasic Mesothelioma

Like all forms of mesothelioma, the extent and severity of symptoms associated with biphasic mesothelioma will vary with the degree of cancer advancement. However, common symptoms of biphasic mesothelioma include shortness of breath, chest pain, tightness in the chest, weight loss, fever and night sweats.

The Role of Image Testing

While image tests cannot diagnose mesothelioma cancer, they can help physicians locate tumors, determine staging and monitor tumor progression. There are a variety of imaging types that can be done.

Common Imaging Tests for Mesothelioma Diagnoses
  • CT scans: Show images of healthy and cancerous tissues.
  • X-rays: Show images of bones and soft tissues, as well as fluid buildup, blockages and other complications.
  • MRI scans: Provide clear, 3D images of a tumor, also showing the contrast of healthy and cancerous tissues.
  • PET scans: Help identify and locate cancerous masses.

The Role of Biopsies

20% – 50% of patients with biphasic mesothelioma are initially classified as epithelioid.

Such inaccuracies can have serious consequences, especially if radical surgery is needed for tumor resection.

When a radiological evaluation and/or laboratory test identifies a potential mesothelioma diagnosis, tumor tissue is then evaluated through a biopsy. A doctor will take a tissue sample to analyze and determine cell type. A biopsy is the only way to definitively diagnose mesothelioma cancer. To diagnose the cancer as biphasic, there must be at least 10% of both epithelial and sarcomatoid cells in the tumor.

An initial biopsy may not be enough for a doctor to recognize biphasic mesothelioma. Since the two cell types are often located in different regions of the tumor, it’s highly possible that a single tissue sample will only show one cell type. In these circumstances, multiple biopsies may be necessary to collect samples of both cell types.

In a recent report, a preoperative needle biopsy classified the cell type correctly only 44% of the time. Thoracotomy was the most accurate, correctly classifying cell type in 83% of cases, followed by thoracoscopy at 74%.

Prognosis and Treatment of Biphasic Mesothelioma

Biphasic mesothelioma typically has a poor prognosis with a life expectancy of around a year. Prognosis is often challenged further by misdiagnosis and late diagnosis, prolonging active treatment. Patients with biphasic tumors that are composed mostly of epithelial cells may experience a longer life expectancy than those composed mostly of sarcomatoid cells, as epithelioid mesothelioma is generally less aggressive and more responsive to treatment options.

Traditional Treatment Options

Commonly pleural-based, biphasic mesothelioma treatment can mimic that of pleural malignant mesothelioma. Traditional modes of treatment include surgery, chemotherapy and radiation therapy.

Traditional Treatments for Mesothelioma
Surgery
  • Physicians use surgery to remove as much of the cancerous material as possible.
  • Common surgeries for mesothelioma include: extrapleural pneumonectomy (EPP), pleurectomy/decortication (P/D), cytoreduction with HIPEC and pericardiectomy
Chemotherapy
  • Chemotherapy is used to kill cancer cells and reduce cancer-related symptoms.
  • Common chemotherapy drugs for mesothelioma include: pemetrexed (Alimta), cisplatin and bevacizumab (Avastin)
Radiation
  • Radiation therapy aims to kill cancer cells and prevent tumors from growing or metastasizing.
  • Common types of radiation therapy include: external beam radiation (EBRT), internal radiation, three-dimensional conformal radiation therapy (3D-CRT), intensity modulated radiation therapy (IMRT) and intraoperative radiation

Typically, care professionals will use multimodal treatment, incorporating a combination of treatment options. Aggressive treatment of patients with mixed mesothelioma may reduce or eliminate epithelioid cells, but often the sarcomatoid component is largely unaffected because the cells are so resistant to treatment. As such, palliative care may be the best course if sarcomatoid mesothelioma cells are dominant.

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Palliative Treatment for Biphasic Mesothelioma

Palliative care focuses on the well-being of the patient, reducing symptoms and providing a higher quality of life. This type of care may be used when the cancer is more advanced, or it may be used alongside traditional modes to reduce negative side effects. For example, chemotherapy has a variety of negative effects and palliative care may help alleviate them.

Traditional treatments can also be applied palliatively, like surgery. Commonly pleural-based, biphasic mesothelioma can cause fluid buildup in the lungs (pleural effusion). Limited surgical procedures, such as pleurodesis or drainage of pleural effusions, may be considered if likely to provide greater patient comfort or relieve labored or painful breathing. Radiation and chemotherapy may also fall into palliative treatment plans to reduce tumor size, providing comfort and relief from associated pains.

Treatment plans for biphasic mesothelioma might also involve pain medications, yoga, meditation and physical therapy to provide physical relief. Support groups and occupational therapy are also considered palliative, providing mesothelioma patients with emotional support as they cope with their diagnosis.