Mesothelioma Types by Tumor Location
Types of mesothelioma cancer differ based on tumor location and tumor cell variant. Pleural mesothelioma is cancer in the pleural lining around the lungs. Mesothelioma most often develops on the outer surface of the lungs. Other sites include the abdomen, heart and testicles.
Peritoneal mesothelioma is cancer in the abdominal lining. This lining is the peritoneum and the second most common site of mesothelioma. Testicular mesothelioma affects the tunica vaginalis lining of the testes. The rarest variant is pericardial mesothelioma, cancer of the protective heart sac.
Each mesothelioma type can lead to different symptoms. Doctors treat mesothelioma by cell type, such as epithelioid or sarcomatoid, and stage.
Mesothelioma prognosis depends on tumor location, cell type and response to treatment. Epithelioid cells are the most common type of cell found in mesothelioma tumors. They are the most responsive to treatment.
Pleural is the most common mesothelioma type. About 70% to 75% of cases occur in the pleura, the outer lung tissue. There are more clinical trial studies on pleural mesothelioma than any other variants.
Aggressive surgery provides the best outcome for early-stage pleural mesothelioma. Unfortunately, doctors often diagnose patients after symptoms appear in later stages.
Typical pleural mesothelioma symptoms include:
- Shortness of breath
- Chest pain
- Weight loss
Most patients qualify for chemotherapy or radiation therapy. Many are also eligible for clinical trials or immunotherapy. These therapies can add months or years to life expectancy. Patients can live for three or more years after stage 1 treatment versus roughly 12 months at stage 4.
Peritoneal mesothelioma forms in the tissue that surrounds the abdominal organs. This variant accounts for 10% to 20% of all cases. The prognosis is better than the pleural type, although less research is available.
Symptoms of peritoneal mesothelioma include:
- Abdominal pain
- Abdominal swelling
- Loss of appetite
- Bowel changes
About half of peritoneal mesothelioma patients are eligible for surgery with heated chemotherapy. This procedure, known as HIPEC, has let patients live five or more years after diagnosis.
The pericardial mesothelioma tumor type is very uncommon. Only about 200 cases exist in medical literature records. This accounts for approximately 1% of all mesothelioma cases. With surgery, some patients live beyond the average six-month life expectancy.
The pericardial form develops in the protective heart sac known as the pericardium. Symptoms of pericardial mesothelioma include:
- Irregular heartbeat
- Chest pain
- Difficulty breathing
Life expectancies of the cases on record range between six weeks and 15 months.
Testicular mesothelioma develops in the outer lining of the testes. Tumors form on tissue called the tunica vaginalis. This form of mesothelioma is the rarest. Less than 100 cases exist in medical literature, making up less than 1% of all mesothelioma cases.
Symptoms include scrotal swelling and painless testicular lumps. Treatment options include surgery and chemotherapy. These therapies can help people live more than two years, on average, after diagnosis.
Three Primary Mesothelioma Cell Types
The three mesothelioma cell types are epithelial, sarcomatoid and biphasic. Biphasic is a mix of the first two cell types.
Asbestos exposure causes the malignant form of mesothelioma cancer. Tumors vary in response to treatment. Epithelial or epithelioid cells respond the best. Sarcomatoid cells are more resistant to treatment.
Cancer doctors take these differences into account when planning your treatment. The incidence and frequency of these cell types vary by cancer location.
Prevalence of Mesothelioma Tumors and Cell Types
|Cell Type||Pleural Tumors||Peritoneal Tumors|
Pericardial mesothelioma exhibits a roughly equal distribution of the three primary cell types. Most testicular cases contain only epithelial cells. The minority are biphasic. There is only one case of sarcomatoid cell disease for this type.
Epithelial Cell Subtype
Epithelioid mesothelioma occurs in 70% to 75% of cases. Patients with epithelioid cell tumors have the best prognosis.
This subtype tends to be less aggressive and doesn’t spread as fast as other cell types.
About 50% of pleural disease is epithelioid. Around 75% of peritoneal tumors are epithelioid.
Sarcomatoid Cell Subtype
Sarcomatoid mesothelioma is the least common mesothelioma cell type. It accounts for around 10% to 20% of all mesothelioma diagnoses. This cell type is the most aggressive and challenging to treat.
Sarcomatous, spindle or diffuse malignant fibrous mesothelioma refer to the same variant.
About 20% of pleural tumors are sarcomatoid. Only about 1% of peritoneal cases are sarcomatous.
Biphasic Cell Subtype
Biphasic mesothelioma refers to tumors that contain epithelial and sarcomatoid cells. Life expectancy for this variant depends upon which of the two appears most.
More epithelioid cells generally mean a better prognosis. If the tumor is high in sarcomatoid cells, it is harder to treat, and life expectancy is shorter.
Around 30% of pleural and 25% of peritoneal tumors are biphasic.
“Sarcomatoid, mixed (biphasic) and epithelial express themselves within the patient in a different manner. It’s important to understand which of these three types the physician is dealing with in a patient.”Dr. Sugarbaker
Rare Mesothelioma Cell Subtypes
Rare cell types are irregular and are more difficult to diagnose. They have subtle differences among them. They may also affect prognosis and life expectancy.
Rare cell subtypes include:
- Well-differentiated papillary cells
- Small cell
Patients with sarcomatoid tumors tend to have shorter life expectancies. Yet, some patients with the lymphohistiocytoid subtype have survived six years or more.
- Well-differentiated papillary cells commonly occur in peritoneal mesothelioma. Only a handful of cases exist of people with other mesothelioma cancer locations.
- 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. 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.
- Adenomatoid cells can occur in both malignant mesothelioma and benign mesothelioma.
- Heterologous cells are present in tumors that may also contain bone, cartilage and soft tissue.
Treatment for rare subtypes depends on the main cell type. For example, lymphohistiocytoid cells respond well to immunotherapy. It also works well on sarcomatoid cells.
Treatment by Type of Mesothelioma
Your specific mesothelioma diagnosis will influence your treatment options. These depend on tumor and cell type.
Doctors must also consider the patient’s age and general health. The provider will also assess the patient’s desires and needs going into treatment.
A proper mesothelioma treatment plan is often multimodal, involving many therapies. Surgery is an appropriate option for patients who are younger and in good health. Chemotherapy, radiation and immunotherapy are available to a broader range of patients.
There are two recommended surgeries for pleural mesothelioma.
- Extrapleural Pneumonectomy: This procedure removes the cancerous lung and nearby structures.
- Pleurectomy and Decortication: A pleurectomy extracts the pleural lining of the lungs. The decortication removes tumors in the chest.
Surgeries also exist for other variants. A peritonectomy removes the abdominal lining. A pericardiectomy removes the outer heart sac. For testicular patients, surgeons perform an inguinal orchiectomy.
Standard chemo involves two drugs. The most common combination for the pleural form is cisplatin and Alimta (pemetrexed). Gemcitabine, carboplatin and other drugs are more effective against the peritoneal variant.
No chemo drug is particularly effective for the pericardial or testicular forms. These types are so rare that there is no standard chemotherapy plan.
A specialist can devise the best chemo plan. They base this decision on treatment history, cancer type and patient health.
Doctors use radiation alongside surgery to slow tumor growth in pleural mesothelioma. Used alone, it can shrink tumors and help relieve symptoms.
Radiation therapy isn’t typical for peritoneal patients. It may harm some organs, such as the kidneys or liver. Radiation can benefit pericardial and testicular patients.
The goal of palliative therapy is to reduce pain and other cancer symptoms. Palliative care can improve a patient’s quality of life and well-being.
One example is thoracentesis. This procedure drains fluid around the lungs. Paracentesis removes fluid from the abdomen. These procedures can ease pain and pressure and make breathing and eating easier.
Common Questions About Types of Mesothelioma
- What is the difference between mesothelioma cell types and tumor location?
Tumor location refers to where the cancer first began growing such as the lining of the lungs or abdomen. Cell type refers to the type of cells that make up the tumors.
- How does the type of mesothelioma impact prognosis and treatment?
The type of mesothelioma a patient has impacts which treatments will be recommended and their overall prognosis. Mesothelioma treatment is complex, and many other factors influence treatment options and prognosis such as the stage of the cancer.
- How can I find a mesothelioma specialist for my type of mesothelioma?
You can speak with a Patient Advocate to find a mesothelioma specialist who has experience treating your type of mesothelioma.