The study of cells is called histology. When doctors study mesothelioma cancer cells it’s called histopathology, the study of diseased cells. Doctors who study diseased cells are called pathologists.
To accurately diagnose and treat mesothelioma, a pathologist carefully studies the cells taken from a patient during a biopsy. The pathologist observes the unique features and behaviors of these sample cells to determine the type of mesothelioma cells present.
Histopathology allows doctors to classify cancer cell types based on what they discover about the cells. This classification tells doctors a lot about the disease and its likely course (prognosis).
Studying a patient’s cells and reaching an accurate diagnosis is critical for applying accurate treatment methods. Based on what doctors learn about the mesothelioma cells, they can implement the best possible treatment plan for their patients.
Histology helps your doctor explain your disease and prognosis. It also allows your doctor to administer treatments to potentially extend your life expectancy and improve your quality of life.
Mesothelioma Cell Types
There are three variations of mesothelioma cancer from a cellular perspective. Different cancer cells form out of the random genetic mutations that occur due to asbestos exposure.
These cell types are:
- Epithelioid mesothelioma
- Sarcomatoid mesothelioma
- Biphasic mesothelioma
Doctors further classify mesothelioma based on cell subtypes.
Mesothelioma cell subtypes include:
- Clear cell
- Small cell
- Acinar cell
- Tubopapillary cell
Cell types differ in how quickly they grow, how likely they are to metastasize (spread), and how they will respond to treatments. A patient’s cell type plays a central role in their prognosis.
Epithelioid mesothelioma is often found in the lining around organs. The epithelioid cells appear in 50 to 70 percent of all mesothelioma cases, making them the most common form of mesothelioma cell. Additionally, they are also the most common cells in pleural mesothelioma cases.
Epithelioid cells grow slowly and respond better to treatment than the other types of mesothelioma cells. Patients solely with epithelial mesothelioma typically have a better prognosis than other patients.
Epithelioid mesothelioma cells typically:
- Have an elongated shape
- Appear uniform under a microscope
- Cling and clump together as they replicate
Epithelioid cells are easier to identify under a microscope than other mesothelioma cell types. They are also slow to metastasize, which makes it easier for treatments like chemotherapy and surgery to kill cancer cells and remove tumors.
Sarcomatoid cells are the least common and most severe mesothelioma cell type. These cancer cells make up 10 to 20 percent of all mesothelioma cases.
Sarcomatoid mesothelioma cells typically:
- Have a long spindle shape
- Appear irregularly under the microscope
- Grow and spread quickly
Sarcomatoid mesothelioma cells resemble the cells from another form of cancer often found in the lungs called pulmonary sarcomatoid carcinoma. As a result, doctors must use extreme care as they study their patients’ cells to avoid confusion with this other cancer type.
Because sarcomatoid cells grow quickly, it makes them difficult to manage as the cancer continues to spread even during treatment. For this reason, mesothelioma sarcomatoid has a poor prognosis. However, new treatments are increasing life expectancy and survival rates.
In roughly 30 percent of mesothelioma cases, tumors contain both epithelioid and sarcomatoid cells. When mesothelioma tumors exhibit characteristics of both cell types, a person will be diagnosed with biphasic mesothelioma. In order to be diagnosed as biphasic, the tumor must be composed of at least 10 percent of each cell type.
Normally, biphasic tumors will:
- Display more characteristics of one type over another (ratio)
- Respond better to treatment if epithelioid cells make up most of the tumor
- Respond worse to treatment if sarcomatoid cells make up most of the tumor
The ratio of biphasic cells has an impact on prognosis as well as treatment decisions. When biphasic cells display more features from epithelioid cells, the patient generally has a longer survival rate.
Prognosis by Cell Type
Cell types are the biggest predictor of prognosis. Because cell types spread at different rates, they each affect the patient differently.
Here are the prognoses and survival rates of each cell type:
- Epithelioid cells have the best prognosis with a one-year survival rate of 60 percent
- Sarcomatoid cells have the poorest prognosis with a median survival rate of six months
- Biphasic cells have the second-best prognosis with life expectancies falling between the other two cell types
Approximately 25 percent of epithelioid mesothelioma patients survive five years or longer. Some sarcomatoid mesothelioma patients have also survived past five years with proper treatment. The life expectancies of patients with biphasic cell mesothelioma depend largely on the ratio of cells.
Treatment Plans Based on Cell Type
Histopathology is a vital component in diagnosing mesothelioma. Studying mesothelioma cancer cells allows doctors to classify the cancer cell type, provide patients with realistic prognoses, and implement effective treatment plans. With this classification, doctors can pursue the most appropriate treatments based on their knowledge of how the cells will react and spread.
Overall, knowing a patient’s mesothelioma cell type empowers doctors to seek the most effective treatments to increase survival rates and improve quality of life.