Biphasic Mesothelioma

Expert Fact Checked

This page was medically reviewed by James Stevenson, M.D. on February 22, 2019. For information on our content creation and review process read our editorial guidelines. If you notice an error or have comments or questions on our content please contact us.

James Stevenson, M.D. Thoracic Medical Oncologist

Biphasic mesothelioma, also known as mixed mesothelioma, is caused by asbestos exposure. 10 – 20% of all mesothelioma cancers are biphasic. The tumors are a combination of epithelioid and sarcomatoid cells. Symptoms, treatment and prognosis vary depending on which of the two cell types is dominant.

01. Biphasic Mesothelioma Explained

What Is Biphasic Mesothelioma?

Biphasic mesothelioma is a specific cell type of mesothelioma cancer. Like all mesotheliomas, biphasic mesothelioma is caused by asbestos exposure.

Example Cell Breakdown of Biphasic Mesothelioma

Biphasic mesothelioma must have at least 10% of epithelioid and sarcomatoid mesothelioma cell types.

So, a patient with 90% epithelioid and 10% sarcomatoid has biphasic mesothelioma. However, a patient with 93% sarcomatoid and 7% epithelioid has sarcomatoid mesothelioma.

Biphasic mesothelioma is a combination of epithelioid and sarcomatoid cells. Specifically, biphasic mesothelioma is any mesothelioma containing at least 10% of both epithelioid and sarcomatoid cells.

Biphasic mesothelioma primarily occurs in the pleura (lung linings) or peritoneum (abdominal linings). However, biphasic mesothelioma tumors may also form in the pericardium (heart lining) or tunica vaginalis (testes).

Regardless of the location, cell pattern depends on the breakdown of epithelioid and sarcomatoid cells. Epithelial and sarcomatoid cells have their own distinct patterns and characteristics.

Biphasic Mesothelioma Cell Pattern: A Combination of Epithelioid and Sarcomatoid

Epithelioid Cell Pattern

  • Cube-like
  • Columnar
  • Flat

Sarcomatoid Cell Pattern

  • Oval
  • Spindle-shaped

The percentage of epithelioid and sarcomatoid cells in biphasic mesothelioma may impact treatment options and prognosis.

02. Biphasic Symptoms

Symptoms of Biphasic Mesothelioma

As with all forms of malignant mesothelioma cancer, symptoms may not present for decades after asbestos exposure.

Mesothelioma patients with biphasic mesothelioma experience symptoms related to the location of their cancer. For example, patients with pleural biphasic mesothelioma may have lung-related symptoms.

Biphasic mesothelioma symptoms include:

The biphasic cell type may also occur in peritoneal mesothelioma cases. Patients with mesothelioma in that location may also experience abdominal pain, abdominal swelling and weight loss.

Other factors, such as overall health, age and pre-existing conditions can also affect cancer symptoms.

03. Biphasic Diagnosis

How Is Biphasic Mesothelioma Diagnosed?

Like all forms of mesothelioma, biphasic mesothelioma is diagnosed through a biopsy.

Prior to a biopsy, mesothelioma diagnosis begins with imaging tests, including X-rays and CT scans. These tests find any visible tumors or excess fluid in the chest cavity or abdomen.

Doctors may also perform blood tests to identify specific biomarkers. These can differentiate mesothelioma from other cancers and conditions.

However, the most important step for an accurate diagnosis is a mesothelioma biopsy. For a biphasic mesothelioma diagnosis, there has to be at least 10% of epithelial and sarcomatoid cells in the tumor.

What Is a Biopsy?

A biopsy is a fluid or tissue sample that is analyzed under a microscope. Biopsies are the only way to definitively diagnose mesothelioma.

Because biphasic mesothelioma has a combination of cell types, multiple biopsies may be needed for a pathologist to recognize the two types of cells.

Multiple Biopsies May Prevent Biphasic Mesothelioma Misdiagnosis

Biphasic tumors are not uniform. This means a single biopsy sample may only consist of one of the two types of cells present. In one study, more than 50% of tumors eventually diagnosed as biphasic were first mistakenly diagnosed as epithelioid. This was due to inadequate biopsy sample size.

One study noted the accuracy of initial diagnosis was dependent on the type of biopsy*:

  • 83% accuracy with a thoracotomy, an invasive surgical biopsy opening the chest cavity to examine the lungs and heart, as well as the surrounding area
  • 74% accuracy with a thoracoscopy, a minimally invasive surgical biopsy, which includes inserting a camera in the chest cavity to examine the area and take a fluid or tissue sample
  • 44% accuracy with a CT-guided biopsy, a minimally invasive procedure during which doctors use imaging tests to assist where to take a fluid or tissue sample

*In this context, accuracy refers to the percentage of initial diagnoses from a given biopsy type that was the correct and final diagnosis for the patient.

Pathologists test biopsy tissue in a number of ways in order to confirm a biphasic mesothelioma diagnosis. This testing often includes immunohistochemistry to detect certain proteins, which may impact patient treatment.

04. Treating Biphasic Mesothelioma

Treatment Options for Biphasic Mesothelioma

Treatment options for patients with biphasic mesothelioma may vary based on cell type percentages and other patient-specific factors.

However, surgery, chemotherapy and radiation therapy are the three common treatments for all types of mesothelioma. A multimodal mesothelioma treatment plan may use some combination of these treatments. However, doctors have seen mixed results using chemotherapy and radiation for biphasic mesothelioma. Both therapies are largely ineffective for sarcomatoid cells. However, the therapies have shown some success in extending life expectancy for epithelioid mesothelioma.

Treatment for biphasic mesothelioma may depend on:

  • Cancer location
  • Severity
  • Overall patient health
  • Percentage of sarcomatoid cells

Mesothelioma doctors will recommend the most appropriate treatment based on the individual patient.

Updates to Treatment Options for Biphasic Mesothelioma

In the past, some researchers suggested all forms of biphasic mesothelioma had a bleak prognosis and should be treated with palliative care. More recently, researchers have found biphasic patients may live for years with appropriate treatment.

Biphasic Peritoneal Mesothelioma Treatment

One of the most successful treatments for peritoneal mesothelioma is combination cytoreductive surgery (CRS) with heated intraoperative chemotherapy (HIPEC).

Previously, doctors believed this treatment wouldn’t be an option for biphasic mesothelioma. Experts recommended treating biphasic cases as if they were sarcomatoid. Sarcomatoid mesothelioma is prone to metastasis and does not respond well to treatment. However, in 2018, researchers found biphasic patients treated with this combination did respond well to treatment.

Median Survival of Biphasic Peritoneal Mesothelioma Patients Treated With CRS & HIPEC

Surgery Success Median Survival
Removal of All Tumors 6.8 years
Removal of Most Tumors 2.8 years

Based on their findings, the researchers recommend the aggressive treatment for patients likely to have successful CRS surgeries. Patients should discuss their eligibility for CRS with their doctors.

Biphasic Pleural Mesothelioma Treatment

Biphasic pleural mesothelioma patients have responded well to immunotherapy treatment.

According to a 2019 study, researchers found pleural mesothelioma patients previously treated with at least one round of chemotherapy experienced extended survival with immunotherapy. Some biphasic mesothelioma patients survived 20 months or more while continuing treatment with nivolumab.

Impact of Sarcomatoid Cells on Potential Biphasic Treatment Options

Sarcomatoid cancer cells do not respond well to treatment. If sarcomatoid cells are the dominant cell type, patients may have limited treatment options. Patients with more than 80% sarcomatoid cells may not be eligible for more aggressive treatments, such as cytoreductive surgery (CRS).

In these instances, a mesothelioma specialist may recommend palliative care. Palliative treatments can relieve symptoms, such as pleural effusion, and improve patient comfort.

Patients and their loved ones may also talk to their doctor about eligibility for potential clinical trials, which may further extend life expectancy.

05. Biphasic Prognosis

Biphasic Mesothelioma Prognosis

Median survival for biphasic mesothelioma is about one year. However, survival varies depending on the location of the cancer and the chosen course of treatment. Studies have reported patients surviving anywhere from 8 months to nearly 7 years after diagnosis. Longer survival times have been reported in more recent studies involving emerging treatment options.

Patients with biphasic mesothelioma often face a wide range of prognoses. This range occurs based on the ratio of epithelioid and sarcomatoid cells. Epithelial cells are typically more responsive to treatment. As such, patients with predominantly epithelial cells often have more favorable prognoses.

Other factors impacting patient life expectancy include:

Patients should discuss their specific case with their doctors. Aligning with their medical team can ensure patients receive the best course of treatments for their goals.