In stage 3, the mesothelioma cancer remains contained near the point of origin in the lining of the lungs (pleura) in a pattern known as a local spread.
Tumors have spread throughout the pleural lining on one side of the chest and to nearby lymph nodes on the same side of the body as the main tumor.
The diaphragm, the heart sac, the area between the lungs (mediastinum) and layers of the chest wall near the main tumor may be affected. The biggest difference between stage 3 and stage 4 mesothelioma is that tumors have not yet spread to distant organs.
Most doctors stage mesothelioma using the American Joint Committee on Cancer’s TNM system. It was updated January 2018. According to that system, stage 3 mesothelioma is divided into two parts: 3A and 3B.
- Stage 3A: Tumors have grown into nearby structures, including the lining of the lung, diaphragm and mediastinum on one side of the chest. The cancer has spread to nearby lymph nodes and possibly layers of the chest wall and the heart sac (pericardium). Surgery to remove all visible tumor growth is still an option.
- Stage 3B: This category is split into two variations depending on the size of the main tumor and spread to the lymph nodes. If the cancer is contained enough to the point of origin or to nearby structures, it may be possible to remove tumors with surgery, even though it has spread to the lymph nodes. In the most advanced point of TNM stage 3, the mesothelioma has grown too extensively at the site of origin to be removed completely with surgery, even if nearby lymph nodes are not affected
Stage 3 Mesothelioma Facts
- Two-year survival rate is between 26-30 percent
- Tumor-removing surgery still a possibility
- Symptoms include frequent chest pain and difficulty breathing
- Emerging treatments through clinical trials may extend survival
At stage 3B, the cancer may have grown into the muscle of the chest wall, ribs, spine or organs between the lungs such as the esophagus, windpipe and thymus. Tumors may also spread through the diaphragm into the lining of the abdomen (peritoneum), to the lung lining on the other side of the chest or through the heart sac into the heart itself.
It is essential to seek treatment as soon as possible following a stage 3 mesothelioma diagnosis.
Once the cancer invades the lymph system or enters the bloodstream, there is a chance that it may spread throughout the chest cavity and to distant organs. This makes it much more difficult to treat.
There is no formal staging system for peritoneal mesothelioma, the second-most-common form of mesothelioma. If a doctor refers to peritoneal mesothelioma as stage 3, it usually means tumors have spread throughout the lining of the abdomen and to nearby lymph nodes.