Development of pleural effusion may be a significant problem in the natural history of mesothelioma. Pleural effusion can cause significant symptoms like breathing difficulty and chest wall pain. Repeated tapping of the pleural fluid may initially control pleural effusion and these symptoms. Chest tube drainage and sclerosis (pleurodesis) may give longer control of the pleural effusion but eventually pleural fluid gets loculated (enclosed in small pockets) and the tumor gradually spreads to occupy the whole pleural space. Removal of pleural fluid may become impossible at this stage of the disease. Patient's symptoms may be disproportionately high compared to the finding in the chest x-ray or CT scan. Treatment with oxygen may not provide much benefit at this stage of the disease because of the shunting effect.
If the pleural effusion does not dominate determine the course of events, with passage of time malignant mesothelioma tend to grow and spread locally. Mesothelioma may spread to the chest wall and tumors may develop on the chest wall. Tumor may invade structures like, esophagus, ribs, vertebrae, intercostals nerves, or the big blood vessels inside the chest causing symptoms related pressure effect on these organs or tissues. Patient may develop abnormalities in clotting mechanisms and may develop blood clots, pulmonary embolism or disseminated intra-vascular coagulation. Some patients may develop high calcium levels. Fever and sweating without any evidence of active infection is very common finding at this stage of mesothelioma. Significant weight loss, deterioration of general performance status, and eventual death may occur.
The median survival after diagnosis of malignant mesothelioma varies widely in different series and range from 4 moths to 18 months. Patients generally die of respiratory failure or pneumonia. Small bowel obstruction due to direct involvement after penetration of diaphragm may occur up to one third of patients. About 10 percent of patients die of pericardial or heart muscle involvement with mesothelioma.
Poor prognostic factors in mesothelioma (If present at the time of diagnosis)
- Pathology report stating sarcomatous histology
- Poor general performance status
- Primary lesion in the pleura
- Presence of weight loss
- Elevation of LDH level to more than 500
- Older age
- Higher stage of disease
- Elevated platelet count
- Presence of chest pain, shortness of breath,
- High white cell count
- Low hemoglobin level
- Male gender
Sarcomatous types as mentioned above are associated with worst prognosis, epithelial cell type has been associated with a better prognosis and mixed types have intermediate prognosis.