Stage 4, defined by Brigham
The cancer has spread far from the point of origin, however there is no specific part that is detailed in the Brigham staging system. It is only known to be widespread.
Stage 4, defined by TNM (aka IMIG)
Along with your pleura and lymph nodes (hilar, mediastinal, subcarinal, bronchopulmonary, and supraclavicular), other areas of your body are also affected. These may include one or more of the following: chest wall, myocardium, pericardium, peritoneum and spine.
Stage 4, defined by Butchart
Cancer has spread far from the origin, traveling to various parts of the body via the bloodstream. Your liver may be affected, along with your brain or bones.
You’ll be very aware of your symptoms at this point, and you may be unable to hold down a job or perform daily activities because you’re feeling so poorly. Symptoms include fever, chest and abdominal pain, breathing difficulties, anorexia, and fatigue. You could also develop cachexia because of condition, a syndrome that makes your body weak and waste away. Organ failure is possible.
Treatment options are very few and can only be determined by a specialist in the disease, but surgery, radiotherapy and chemotherapy are common. Surgery is not considered an option because of how widespread it has become, however if it is performed its point would be to improve your comfort rather than remove the cancer and cure you. For example, you may undergo surgery to remove a tumor to decrease chest pain and improve your breathing ability. Your doctor will design a treatment plan with the purpose of improving your comfort by minimizing the pain you experience from your symptoms, because by this time your condition is considered terminal.
Your chances of survival
If you are diagnosed with stage 4 mesothelioma, you may have a year or less to live.