There are four types of mesothelioma: Pleural (in the linings surrounding the lungs), peritoneal (in the lining of the abdominal cavity), pericardial (in the sac surrounding the heart) and testicular (in the lining covering the testes). Mesothelioma is also identified by three cell types that compose tumors: Epithelioid, sarcomatoid and biphasic. These factors affect your prognosis, and your oncologist considers them when creating your treatment plan.
Then people refer to the different types of mesothelioma, they are usually talking about the different places in the body where mesothelioma develops. But things can get a little confusing because there are different cell types of Mesothelioma which may arise in each location too.
The cell type of your cancer is identified during biopsy testing and is important to accurately identify mesothelioma and optimally treat the cancer.
The treatment plan your doctor recommends will depend mostly on the location of your cancer. Your cell type, age, overall health and cancer stage will play a role.
KEY FACTS ABOUT THE TYPES OF MESOTHELIOMA
- Mesothelioma is most likely to develop in the linings around the lungs and abdomen.
- The most common cell type, epithelioid, is also the most responsive to treatment.
- Treatment is tailored to your specific type of mesothelioma, right down to the microscopic cells that make up the cancer.
- Clinical trials may recruit participants based upon their type of mesothelioma.
Four Types of Mesothelioma Identified by Location
The type of mesothelioma you are diagnosed with is named after the place it developed. For example, when the cancer forms in the pleural lining around the lungs, it is called pleural mesothelioma.
- Pleural (lungs)
- Peritoneal (abdomen)
- Pericardial (heart)
- Testicular (testes)
Between 2,500 and 3,200 cases of mesothelioma are diagnosed annually in the United States. Pleural mesothelioma accounts for approximately 75 percent of cases, and peritoneal accounts for 10 to 20 percent. Only 1 percent of cases arise from the pericardial sac around the heart or the lining covering the testicles.
However, incidence varies from year to year. In a 2015 study analyzing mesothelioma incidence from 2003 to 2008, approximately 85 percent of cases were pleural, and 7 percent were peritoneal.
Each type of mesothelioma presents different symptoms. Treatment is tailored by type, and the prognosis varies as well.
Pleural Mesothelioma
- Location: Pleural lining
- Symptoms: Breathlessness, chest pain, fever and fatigue
- Prognosis: 3+ years at stage 1 vs. 12 months at stage 4
Because it is the most common type of mesothelioma, there has been plenty of research conducted on the pleural form. Most patients qualify for chemotherapy, radiation therapy and immunotherapy, which can add months or years to life expectancy.
Peritoneal Mesothelioma
- Location: Lining of the abdominal cavity
- Symptoms: Abdominal pain and distention, bloating and bowel changes
- Prognosis: 52 percent live at least five years after surgery with HIPEC
Even though less research has been conducted on this type compared to pleural, the prognosis for peritoneal is better. Numerous studies show around half of patients who undergo a combination of cytoreductive surgery and heated chemotherapy (HIPEC) survive five years or more.
Peritoneal mesothelioma occurs more commonly in women than men. The peritoneal type accounts for 7 percent of mesothelioma cases in men and 17 percent of mesothelioma cases in women.
Pericardial Mesothelioma
- Location: Linings of the sac around the heart
- Symptoms: Irregular heartbeat, chest pain, difficulty breathing and cough
- Prognosis: Typically ranges from six weeks to 15 months
The pericardial type is extremely rare. Around 200 cases are reported in medical literature. Surgery helps some patients live for years beyond the average six-month survival rate.
Testicular Mesothelioma
- Location: Arises in the tunica vaginalis, which is the lining covering a testicle
- Symptoms: Scrotal swelling, painless testicular lumps
- Prognosis: 2 years
Testicular mesothelioma develops in the tunica vaginalis, which is the surface lining of the testes. Less than 100 cases are reported in medical literature. Treatment involves surgery and chemotherapy, which helps people live more than two years on average.
Three Types of Mesothelioma Cells
There are three types of cells that comprise mesothelioma tumors:
- Epithelial
- Sarcomatoid
- Biphasic
Epithelioid and sarcomatoid cells respond differently to treatment. Epithelial cells respond the best, and sarcomatoid cells are more resistant to treatment. This difference is why doctors consider your cell type when recommending a treatment plan.
Incidence of these cell types varies depending upon location. When it comes to pleural mesothelioma, about 50 percent are epithelioid, 30 percent are biphasic and 20 percent are sarcomatoid. Peritoneal mesotheliomas are about 75 percent epithelioid, 24 percent biphasic and 1 percent sarcomatoid.
Pericardial mesothelioma appears to have a roughly equal distribution of the three cell types. Approximately two-thirds of testicular mesothelioma cases involve epithelioid cells, and the rest are biphasic. Only one case of purely sarcomatoid cells was reported in testicular mesothelioma.
Certain subtypes of these cells are correlated with different types of mesothelioma. For example:
- Well-differentiated papillary cells occur most commonly in abdominal mesothelioma. Only a handful of cases have been reported in people with mesothelioma of the pleura, pericardium or testicles.
- Small cell mesothelioma is another cell type that occurs more commonly in the abdomen.
- A little more than half of the cases of deciduoid mesothelioma occur in the abdomen and slightly less than half arise in the lung lining.
- Cystic and papillary cells are more common in peritoneal mesothelioma.
- Desmoplastic and lymphohistiocytoid are more common in pleural mesothelioma.
Treatment Tailored to Your Type of Mesothelioma
The type of mesothelioma you are diagnosed with will influence your treatment options. Different procedures, anti-cancer drugs and radiation therapy are used depending upon the location of your cancer.
Surgery to remove tumors is different for each type of mesothelioma. Extrapleural pneumonectomy and pleurectomy/decortication are used to remove pleural tumors. Peritoneal tumors are removed with a peritonectomy, pericardial tumors are removed with a pericardiectomy, and testicular tumors are removed with an inguinal orchiectomy.
Different chemotherapy drugs are used to treat pleural and peritoneal mesothelioma. A combination of cisplatin and pemetrexed is the most effective treatment against pleural mesothelioma. Combinations of gemcitabine, pemetrexed, mitomycin and carboplatin are most effective against peritoneal mesothelioma. No particular chemotherapy regimen is consistently effective for pericardial or testicular mesothelioma. The two latter types of mesothelioma are so rare that they have not been available for studies.
Different approaches to radiation therapy are used for all types of mesothelioma. In pleural mesothelioma, radiation therapy is used when surgery is an option or when tumors have invaded the chest wall. Radiation therapy hasn’t proven successful or very safe for peritoneal mesothelioma, but it has been used successfully to treat pericardial and testicular mesothelioma.
Different procedures are used to drain fluid buildup from around the lungs and abdomen. Fluid around the lungs is drained with a thoracentesis, while a paracentesis is used to drain fluid from the abdomen.
***
Your cancer’s cell type influences treatment in a less direct way than the location. Instead, oncologists consider your cell type when deciding how aggressively they can treat your cancer. Because epithelioid cells respond the best to treatment, patients with epithelial mesothelioma are more often considered for aggressive treatment plans. Because sarcomatoid cells respond poorly to treatment, patients with this type are less often considered for aggressive treatment.
Other factors, such as the stage of your cancer, your age and overall health, play a role in which treatments are recommended. Surgery is recommended to early stage patients who are younger and in good health. Chemotherapy, radiation therapy and immunotherapy are available to every patient regardless of stage or age.