Biphasic Mesothelioma

What Is Biphasic Mesothelioma?

Biphasic mesothelioma is a cell type that contains a combination of epithelial and sarcomatoid cells. As with all mesothelioma cell types, asbestos is the main cause.

The life expectancy of patients with biphasic mesothelioma varies. It depends on the ratio of epithelial to sarcomatoid cells. A 2021 trial of the immunotherapy drugs Opdivo (nivolumab) and Yervoy (ipilimumab) found that biphasic patients had a median survival of 18.1 months.

The more sarcomatoid cells there are, the worse the prognosis. This cell type is more common in pleural cases than in peritoneal cases. Biphasic is the second most common type of mesothelioma.

Knowing the type of mesothelioma and its diagnosis can help. It can lead to better treatment choices with your doctor. Researchers call the study of these cells mesothelioma histology.

Key Facts About Biphasic Mesothelioma

• Combination of epithelioid and sarcomatoid mesothelioma cells.
• It is the second-most common type of mesothelioma.
• Nearly 30% of pleural mesothelioma tumors and 25% of peritoneal tumors are biphasic.
• Prognosis and life expectancy for biphasic mesothelioma depends on the ratio of epithelial and sarcomatoid cells.

Characteristics of Biphasic Mesothelioma

In biphasic mesothelioma, pathologists find epithelioid and sarcomatoid cells near each other. They can also appear in separate areas of a tumor.

Among the sarcomatoid cells are scattered areas of epithelial cells. These areas usually consist of solid and tubopapillary cells. They are epithelial subtypes. The ratio of epithelial to sarcomatoid cells can vary greatly.

Many experts believe that biphasic mesothelioma is more common. The diagnosis could be more common if more areas of mesothelioma tumors were sampled.

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Diagnosing the Biphasic Cell Type

A biopsy may collect only a small tissue sample for lab study. Testing samples from just one location offers a limited view of the type and amount of mesothelioma cells. The biphasic cell type can be hard to detect and diagnose for this reason.

A more accurate mesothelioma diagnosis involves tissue samples from several parts of the tumor. It’s vital to identify the specific cell type. It can affect your treatment options and outlook.

A 2021 study found that membranous HEG1 staining helped diagnose biphasic mesothelioma. It coud identify 92.3% of biphasic cases apart from all carcinomas. It also identified 98.7% of biphasic cases apart from lung carcinomas.

Preventing a Misdiagnosis

Doctors use advanced tests to identify biphasic cases. Immunohistochemistry can distinguish biphasic mesothelioma from similar diseases. It detects certain proteins and reveals abnormal cells. This information allows doctors to rule out common misdiagnoses, including cancers such as synovial sarcoma and carcinosarcoma.

A 2011 study found that doctors can misdiagnose the biphasic type after a biopsy. The study found that only 26% of biphasic patients got an accurate diagnosis. The authors said that surgical biopsy best identifies these cases. The initial diagnostic methods were thoracoscopy, thoracotomy, CT scans and other biopsies.

Biphasic Mesothelioma Treatment

Patients with biphasic mesothelioma may not get aggressive treatment. The reason is that biphasic has a slightly poorer prognosis than epithelioid cases. However, doctors base treatment on more than just cell type. Treatment may also depend on the tumor’s stage and location.

Treatment of Biphasic Mesothelioma

• Chemotherapy: Biphasic cases with more epithelial cells respond better to chemo.
• Immunotherapy: It helps pleural cases live at least 18 months. But, it isn’t approved for peritoneal cases yet.
• Radiation: Patients on multimodal therapy have a lower risk of local recurrence with radiation.
• Surgery: Early-stage cases benefit the most from surgery.

Clinical trials are testing new drugs for mesothelioma patients with sarcomatoid or biphasic tumors.

For example, one phase II/III trial tests an anti-cancer enzyme on sarcomatoid and biphasic mesothelioma tumors. ADI-PEG 20 (pegylated arginine deiminase) is an enzyme. It significantly improved the survival of sarcomatoid patients in its phase I trial.

Biphasic Prognosis and Life Expectancy

The prognosis for biphasic mesothelioma depends on the ratio of epithelial to sarcomatoid cells 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.

Research On Biphasic Mesothelioma Survival

• Clinical Lung Cancer: PD-L1 levels may partly affect the poor prognosis. A 2019 study found that pleural mesothelioma patients with sarcomatoid and biphasic cells had higher levels of PD-L1. Researchers linked this to shorter survival.
• Journal of Clinical Pathology: Pure sarcomatoid tumor patients survived 5.8 months. Those with biphasic tumors survived 6.8 months. The epithelial cells in biphasic cases resulted in a one-month survival advantage.
• Lung Cancer International: This study found that cell type affects lifespan. On average, epithelial mesothelioma patients survive 200 days longer than those with biphasic or sarcomatoid cells.
• Science Reports: A 2021 phase III trial of the immunotherapy drugs Opdivo and Yervoy reported that patients with the sarcomatoid or biphasic cell type had a median survival of 18.1 months. In contrast, those on standard chemotherapy had a median survival of just 8.8 months.

Another factor in the poor prognosis of biphasic mesothelioma is that sarcomatoid cells spread faster than epithelial cells. Biphasic tumors with a high ratio of sarcomatoid cells may spread quickly. This factor may result in shorter life expectancy.

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