The early symptoms of mesothelioma are generally non-specific, and may lead to a delay in diagnosis. Sometimes resembling viral pneumonia, pleural mesothelioma patients may present with shortness of breath, chest pain and/or persistent cough; some patients show no symptoms at all. A chest x-ray may show a build-up of fluid or pleural effusion (discussed below). The right lung is affected 60% of the time, with involvement of both lungs being seen in approximately 5% of patients at the time of diagnosis. Less common symptoms of pleural mesothelioma include fever, night sweats and weight loss. Symptoms of peritoneal mesothelioma may include pain or swelling in the abdomen due to a build-up of fluid, nausea, weight loss, bowel obstruction, anemia or swelling of the feet.
PLEASE KEEP IN MIND THAT THESE SYMPTOMS MAY BE CAUSED BY MESOTHELIOMA OR BY OTHER LESS SERIOUS CONDITIONS. ONLY A DOCTOR CAN MAKE A DEFINITIVE DIAGNOSIS.
One of the most common symptoms of mesothelioma is a pleural effusion, or an accumulation of fluid between the parietal pleura (the pleura covering the chest wall and diaphragm) and the visceral pleura (the pleura covering the lungs). Both of these membranes are covered with mesothelial cells which, under normal conditions, produce a small amount of fluid that acts as a lubricant between the chest wall and the lung. Any excess fluid is absorbed by blood and lymph vessels maintaining a balance. When too much fluid forms, the result is an effusion.
Pleural effusion is broken down into two categories, transudates and exudates. A transudate is a clear fluid that forms not because the pleural surfaces are diseased, but because of an imbalance between the normal production and removal of the fluid. The most common cause of transudative fluid is congestive heart failure. An exudate, which is often cloudy and contains many cells and proteins, results from disease of the pleura itself, and is common to mesothelioma. To determine whether a fluid is a transudate or exudate, a diagnostic thoracentesis, in which a needle or catheter is used to obtain a fluid sample, may be conducted.
As the volume of fluid increases, shortness of breath, known as “dyspnea”, and sometimes pain, ranging from mild to stabbing, may occur. Some patients may experience a dry cough. When the doctor listens to the patient’s chest with a stethoscope, normal breath sounds are muted, and tapping on the chest will reveal dull rather than hollow sounds.
Diagnosis of pleural effusion is usually accomplished with a simple chest x-ray, although CT scans or ultrasound may also be used. A special x-ray technique, called a lateral decubitus film, may be used to detect smaller effusions or to enable the physician to estimate of the amount of fluid present. If the underlying cause of the effusion is readily apparent (such as in the case of severe congestive heart failure), sampling of the fluid may not be necessary, however, because pleural effusion may be symptomatic of a number of disease processes from benign to malignant, a fluid sample is generally taken. Diagnostic thoracentesis, in which cells are extracted from the pleural cavity, is commonly done when the possibility of mesothelioma exists, however, in up to 85% of cases, the fluid tests negative or inconclusive even though cancer is present. It is ultimately a needle biopsy of the pleura (lining of the lung) or an open surgical biopsy which confirms a mesothelioma diagnosis.
Pleural effusion caused by heart failure or infection can usually be resolved by directing treatment at the cause, however, when testing has realized no diagnosis, and fluid continues to build or recur, doctors may recommend chest tube drainage and chemical pleurodesis. Chemical pleurodesis is a technique in which a sclerosing agent is used to abrade the pleural surfaces producing an adhesion between the parietal and visceral pleurae. This will prevent further effusion by eliminating the pleural space. Talc appears to be the most effective agent for pleurodesis, with a success rate of nearly 95%. It is highly effective when administered by either poudrage or slurry. Poudrage is the most widely used method of instilling talc into the pleural space. Before spraying the talc, the medical team removes all pleural fluid to completely collapse the lung. After the talc is administered, they inspect the pleural cavity to be sure the talc has been evenly distributed over the pleural surface. Some doctors prefer to use talc mixed with saline solution which forms a wet slurry that can roll around the pleural cavity.
Sources for information on this page:
“Malignant Mesothelioma” Harvey I. Pass, Nicholas J. Vogelzang, Michele Carbone, entire book, not available on-line
National Heart Lung and Blood Institute – Asbestos-Related Lung Diseases
Centers for Disease Control – Malignant Mesothelioma Mortality – United States, 1999-2005
Journal of Thoracic Oncology – Screening for malignant pleural mesothelioma and lung cancer in individuals with a history of asbestos exposure.
National Cancer Institute: Advanced Malignant Mesothelioma
Personal contact with practicing oncologists