The majority of patients with pleural mesothelioma, treated or untreated die of complications of local disease due to increasing tumor bulk that eventually replaces the pleural effusion and causes progressive respiratory compromise (difficulty breathing), pneumonia, or myocardial (heart) dysfunction with arrhythmias (unusual heart rhythms) and/or unrelenting chest wall pain requiring narcotics, which leads to cachexia (wasting syndrome), and dysphagia (difficulty breathing) from tumor compressions of the esophagus. The most important predictor of survival (prognostic indicator) is performance status. In oncology and other medical fields, performance status is an attempt to quantify cancer patients' general well-being (i.e. can they dress themselves, are the bedridden, etc.?)
The median survival of 337 patients treated in ten clinical trials by the Cancer and Leukemia Group B (all of whom were require to be performance status 0, 1 or 2) was seven months. However, for those with performance status 0, the median survival was 13 to 14 months. In various series, the median survival varies from four to eighteen months (range, weeks to 16 years), but performance status was rarely reported in older series. Patients generally die of respiratory failure or pneumonia. Small bowel obstruction from direct extension through the diaphragm develops in approximately once-third of patients, and ten percent die of pericardial or myocardial involvement.
Extrathoracic metastases (psread of the cancer outside of the lung area) occur late in the course of disease and are not usually the direct cause of the patient’s death. In the largest series of patients with metastatic pleural mesothelioma who had autopsy, 54% to 82% had distant metastases, with the most frequently involved organs being the liver, adrenal gland, kidney, and contralateral lung (lung on the opposite side from where the cancer was initially found). Intracranial (inside the scull) metastases are seen in about three percent of patients and are predominantly of the sarcomatous type.