Biphasic mesothelioma is defined by the presence of both epithelioid and sarcomatoid cells, with characteristics and behaviors that are consistent with the most dominant of the two cell types. Varying treatment options from surgery, radiation therapy and chemotherapy may be administered, with the most favorable prognosis occurring in cases with higher proportions of epithelial over sarcomatoid cells.
Biphasic Cell Type Overview
Mesothelioma cell type helps doctors determine your prognosis and potentially how to treat your unique case.
If you’ve been diagnosed with mixed, or biphasic, cell type, here is what you need to know:
- Biphasic cell type is the second most common mesothelioma
- Biphasic mesothelioma is made up of epithelioid and sarcomatoid cells
- Biphasic tumors take on the characteristics and behaviors of the dominant cell type
- Prognosis is more favorable with higher proportions of epithelioid cells versus sarcomatoid cells
- Possible treatment plans for biphasic cell type include surgery, chemotherapy and radiation therapy
What is Biphasic Cell Type?
Mesothelioma is a cancer that starts in cells in the lining of the chest, abdomen and the space around the heart. Three cell types exist within cases of mesothelioma, epithelioid, sarcomatoid and biphasic. Each cell type has different characteristics and behaviors and therefore has different treatments and prognosis.
Biphasic cell type contains both epithelioid and sarcomatoid cells, and is the second most common form of mesothelioma. A tumor must contain at least 10% or either epithelioid or sarcomatoid cells to be defined as biphasic. Biphasic mesothelioma accounts for around 30% of cases, with tumors containing higher quantities of epithelial cells having a more favourable prognosis than high quantities of sarcomatoid.
Biphasic tumors are frequency misdiagnosed, as epithelioid and sarcomatoid cells tend to grow in different parts of the tumor. Normally only one cell type ends up in an extracted tissue sample.
To accurately diagnose biphasic type, doctors need to take samples of different parts of the tumour and view the sample under a microscope to increase the chance of viewing all cells present in the mass. The tumor sample may also be tested for numerous proteins, a procedure called immunohistochemistry that is used to ensure proper diagnosis.
Tumor location, cancer stage, and mesothelioma cell type are all important factors of mesothelioma overall diagnose. Epithelioid, sarcomatoid and biphasic cell types all have different characteristics and behaviors that respond differently to treatment, so diagnosing cell type is an important step for in the development of treatments plans that deliver the best prognosis.
Biphasic Cell Type Characteristics
When a patient presents symptoms that are typically presented in varying forms of cancer, a biopsy is performed and collected tissues are studied under a microscope. Cellular characteristics are observed to ensure a proper diagnosis can be made.
Biphasic tissue samples are often difficult to diagnose as epithelioid and sarcomatoid cells grow in different areas of the tumor. Large biopsy samples, sometimes collected through surgery, need to be taken from different areas of tumor to identify both cell types.
Even if both cell types are identified, biphasic mesothelioma needs to be differentiated from cancers such as synovial sarcoma, a rare cancer occurring in joints in the arms or legs, and carcinosarcomas, a cancer with a mixture of epithelial and connective tissue cells. For these reasons, multiple screening tests and biological markers are used to accurately diagnose biphasic mesothelioma to ensure proper treatment plans are administered.
When viewed under a microscope, biphasic tumor samples take on the characteristics of whatever the dominant cell type is—either epithelioid or sarcomatoid. If the majority of the biphasic tumor is made up of epithelioid cells, most of the microscopic cells will appear cube-like with visible nuclei (the cells DNA) and pink cytoplasm (the material that fills the cell). If sarcomatoid cells are found in the highest proportion, cells will appear irregular and spindle-shaped when viewed under a microscope. Both epithelioid and sarcomatoid cells can be differentiated more by subtypes, which are described in more detail below.
Biphasic Cell Type Behavior
As with biphasic characteristics, biphasic behaviors have similarities with epithelioid or sarcomatoid cells—depending on which is found in a greater abundance. How biphasic mesothelioma behaves has a large effect on overall prognosis, with life expectancy and survival rates being higher when biphasic tumors that have higher proportions of epithelioid cells over sarcomatoid.
You can expect biphasic tumors that are epithelioid-dominant to contain cells that replicate quick but spread slow. The cube-like cells tend to replicate on top of each other forming masses that lack mobility. In contrast, when a biphasic tumor is sarcomatoid-dominant, cells will tend to form small nodules or lumps and rarely present as large masses. This behavior means that sarcomatoid cells are able to spread quickly throughout the body, and are defined as the most aggressive cell type.
Biphasic cell type is made up of epithelial and sarcomatoid cells, which each contain varying subtypes. When viewing a biphasic tumor sample under a microscope epithelioid and sarcomatoid subtypes can be identified, which can help doctors with disease diagnosis and choosing the most effective treatment methods.
Cell subtypes have unique characteristics and are sometimes found in specific locations. It is important to correctly identify epithelioid and sarcomatoid subtypes if they are present in a biphasic mass, as research has shown that subtype is an important factor in overall disease prognosis.
Epithelioid subtypes include tubulopapillary, acinar, solid, deciduoid, micropapillary, trabecular, cystic, adenomatoid, glandular, clear and small.
Sarcomatoid subtypes include desmoplastic, osteosarcomatous, chondrosarcomatous, and lymphohistiocytoid.
Biphasic Cell Type Prognosis
When it comes to mesothelioma prognosis, there are many variables that determine factors such as life expectancy and survival rate. Some of these variables come from distinctive traits, such as age, gender and medical history in relation to previous reactions to treatment. Mesothelioma disease variables, such as tumor location, stage of cancer and cell type also affect a patients prognosis.
Biphasic mesothelioma has the second best prognosis between the three possible cell types. The average survival rate of patients diagnosed with biphasic mesothelioma is between 11 and 15 months.
As sarcomatoid cells are aggressive and less responsive to treatment, biphasic cases with higher proportions of these cells generally have a worse prognosis when compared to higher ratios of epithelioid cells. Studies have shown that prognosis can improve if cases are caught at an early stage and survival rates may be better when tumors are located in the abdomen over the chest and heart.
Biphasic cell type prognosis is also impacted by how accurately the disease is diagnosed. In a recent study involving patients with pleural mesothelioma, of the 19 that had biphasic cell type, only 5 of them were accurately diagnosed. Achieving a proper diagnosis is imperative if a proper treatment plan is to be developed to achieve the best possible prognosis.
Treatment for Biphasic Mesothelioma
Treatment plans with combinations of surgery, chemotherapy and radiation therapy, an approach called multimodal, is commonly used to treat mesothelioma across all cell types. Biphasic mesothelioma can be a complicated mesothelioma cell type to treat, depending on the proportion of epithelioid and sarcomatoid cells present.
With cases of biphasic mesothelioma that are epithelioid dominant, doctors may recommend aggressive treatment methods as this cell type generally responds well to treatment. Treatment plans for this variation of biphasic mesothelioma may include a mixture of surgery, chemotherapy, and radiation therapy to attempt to either remove or shrink the cancerous cells.
In occurrences of biphasic cell type with a higher occurrence of sarcomatoid cells, treatment options are more limited. Sarcomatoid cells do not typically grow as single masses and generally spread throughout the body in small lumps. This behavior makes it difficult to remove sarcomatoid cells with surgery, and accurately locate the cells to administer radiation therapy.
The aggressive cells can sometimes respond well to chemotherapy, an anti-cancer drug that destroys the replication mechanisms within cancerous cells, however multiple therapy rounds may be needed. In both scenarios of biphasic mesothelioma, doctors will usually develop multimodal treatment plans.
Treatment options will vary between patients depending on their age, overall health and previous reactions to surgeries and other types of treatment. Biphasic tumor location and stage may also have an impact on the treatment plan a patient may receive.
For more information on undergoing mesothelioma treatment for biphasic cell type, contact our Patient Advocates today.