Mesothelioma Stages

* Stage 1a mesothelioma affects the outer layer of the pleura around the chest wall, on one side of the chest only. It may have grown in the pleural tissue covering the diaphragm

* Stage 1b mesothelioma has started to spread to the inner pleural layer (closest to the lungs), but remains on one side of the chest.

* Stage 2 mesothelioma has spread to both layers of the pleura on one side of the body, and has enlarged to form a tumour mass on the pleural tissue around the lungs, or has started to spread into the diaphragm muscle or the lung tissue

* Stage 3 mesothelioma has spread to the chest wall or the covering of the heart (pericardium), but is still potentially removable by surgery. Or it has spread to the lymph nodes on the same side of the chest

* Stage 4 mesothelioma cannot be removed by surgery because it has spread to different parts of the chest wall, or grown through the diaphragm into the peritoneum, or to the pleura on the other side of the body, or to the chest organs, or through to the inner layer of the pericardium. Or it has spread to the lymph nodes on the other side of the chest, or above the collarbone. Or has spread to other parts of the body.