Mesothelioma tend to grow and spread in unusual ways compared to other tumors. Rather than forming a "lump", mesothelioma tends to extent from the pleural lining to press against the lung or abdominal organs. It also grows along the pleural lining, eventually forming a hard casing around the lung and making it difficult for patients to take a deep breath. Mesothelioma generally does not spread widely to other organs but, rather, tends to extensively involve the chest and lungs or abdominal cavity before spreading to other distant organs, late in the course of the disease.
If the disease is detected early, when only limited growth on the pleural lining has occurred (stage I), the tumor is considered potentially curable and an attempt can be made to surgically remove the entire tumor. Usually, however, the tumor is detected later, when it more extensively involves the pleural lining and has possibly invaded surrounding normal structures. In these advanced stages (stages II, III and IV), the cancer significantly impacts the quality of life.