What Is Stage 3 Mesothelioma?

Most cases are diagnosed at stage 3, primarily due to worsening symptoms. As with other cancers staged on a 1 through 4 scale, stage 3 mesothelioma is considered an advanced stage. The cancer is no longer contained to its original location in the body but has not spread to the other side of the body or to distant organs. This is referred to as local spread.

At stage 3, treatment may or may not include resective surgery, supported with chemotherapy or radiation. Palliative care and clinical trials may also be effective therapeutic options for patients at this stage. Speak with your doctor right away to decide on a custom treatment plan.

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By Type

The location of mesothelioma in your body will make a difference in how the tumors develop.

This is an image of a lung with stage 3 cancer.

Stage 3 Pleural Mesothelioma

Pleural mesothelioma accounts for between 70 and 90 percent of all cases of the disease. It affects the pleura (lining of the lungs and chest) and is the only type with a defined staging system.

Although the Brigham and Butchart systems are sometimes used for staging the disease, the TNM staging system has become widely accepted as the most effective staging system. It evaluates the extent and location of the tumors, lymph node involvement, and metastasis (spread) of the cancer.

When diagnosed at stage 3, the tumor has grown into nearby tissues and organs. Depending on the cancer’s progression, surgical removal may still be an option. It has likely reached the lymph nodes, diaphragm, and potentially the heart sac but remains localized (not reaching distant organs).

The TNM scale categorizes stage 3 pleural mesothelioma into two groups — Stage 3A and Stage 3B.

Stage 3A

  • The primary tumor is still likely resectable
  • Spread is localized to one side of the chest cavity, potentially reaching the lymph nodes or diaphragm
  • Cancer may have reached the pericardium (heart sac)
  • No distant spread

Stage 3B

  • Metastasis may be too extensive for resective surgery
  • Spread may be more expansive, reaching into the abdomen or other nearby organs
  • Lymph nodes are affected (this is significant because cancer can spread to other parts of the body through the lymphatic system)
  • No distant spread

This is an image of stage 3 peritoneal mesothelioma.

Stage 3 Peritoneal Mesothelioma

When tumors develop in the abdomen rather than the chest cavity, it’s called peritoneal mesothelioma. This form is rare, accounting for only about 660 cases annually. For this reason, there is no defined staging system in place.

Doctors look to the Peritoneal Cancer Index (PCI) for staging peritoneal mesothelioma. It measures the extent of metastasis and provides a score between 0 and 39. A low score represents a less aggressive cancer. Stage 3 patients usually have a PCI score in the range of 21 to 30.

The PCI score helps doctors determine a patient’s course of treatment.

This is an image of stage 3 pericardial mesothelioma.

Stage 3 Pericardial Mesothelioma

Pericardial mesothelioma, an extremely rare form of the disease affecting the lining of the heart, accounts for less than 5 percent of all cases. Doctors typically use the American Joint Committee on Cancer (AJCC) 1 through 4 staging scale when evaluating pericardial cases.


Symptoms at stage 3 become more intense than in stages 1 or 2. For this reason, stage 3 is commonly when most patients see a physician and receive a diagnosis.

Stage 3 mesothelioma symptoms include:

  • A persistent dry cough
  • Anemia
  • Blood clots
  • Body aches
  • Coughing up blood (hemoptysis)
  • Difficulty breathing
  • Fatigue
  • Fever
  • Fluid buildup in the chest or abdominal cavities
  • Night sweats
  • Severe chest or abdominal pain
  • Shortness of breath (dyspnea)
  • Unexplained weight loss

If you or a loved one are experiencing any of the above symptoms — especially if there is a work history around asbestos  — visit a doctor right away.

Stage 3 Survival Rates

The life expectancy for stage 3 mesothelioma patients is approximately 16 months. However, every case is different, and there are many factors that affect a doctor-given prognosis. It’s important to stay hopeful and remember that many patients have exceeded their initial prognoses. Clinical trials and emerging treatments may also offer life-extending treatment options for patients living with stage 3 mesothelioma.

Treating Stage 3 Mesothelioma

The extent of metastasis plays a big role in determining a patient’s treatment plan. When the tumors are still potentially resectable (able to be removed), doctors may treat cancer with surgery. Chemotherapy and radiation are commonly used as well to shrink the tumors and prevent the proliferation of new ones.

Immunotherapy may also be an option at this stage. This form of treatment boosts the body’s own immune system in an effort to fight off and prevent the spread of cancer cells. Other clinical trials may be available to test emerging treatments on stage 3 patients.

If the doctor determines that the cancer is no longer resectable, they may turn their focus to palliative care.

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