Pleural effusion is the accumulation of fluid in the pleural space. The pleural space is the region between the outer surface of each lung (visceral pleurae) and the membrane that surrounds each lung (parietal pleurae). Under normal conditions, the pleurae are kept wet with pleural fluid to allow movement of the lungs within the chest. The pleural fluid comes from cells that make up the pleurae. Pleural fluid is continuously being produced and removed, a process that is precisely controlled by many factors. Cancer can interfere with this delicate balance within the pleural space causing fluid to accumulate.
Cancer is responsible for 40% of all pleural effusions, which are then called malignant pleural effusions. Pleural effusion is the first symptom of cancer for up to 50% of the patients. Thirty-five percent of the cases of malignant pleural effusion are caused by lung cancer, 23% by breast cancer, and 10% by lymphoma.
Chest x rays and computed topography scans may be performed to diagnose pleural effusion. Thoracentesis, the removal of pleural fluid through a long needle, is usually performed for diagnostic purposes. Fluid removed by thoracentesis will be sent to the lab to be thoroughly evaluated. Thoracoscopy, in which a wand-like lighted camera (endoscope) is inserted through the chest, may be conducted to diagnose pleural effusion. During thoracoscopy, samples (biopsy) of pleura may be taken.
Pleural effusion can hinder the normal function of the lungs. Symptoms of pleural effusion include chest pain, chest heaviness, breathing difficulties, and a dry cough. Patients with malignant pleural effusions tend to be weak and have a short-span life expectancy. The prognosis depends on the type of cancer. Sixty-five percent of patients with malignant pleural effusions die within three months and 80% die within six months. However, patients with pleural effusion related to breast cancer have a longer life expectancy.
Malignant pleural effusions are most often associated with lymphomas, leukemia, breast cancer, gastrointestinal cancer, lung cancer, and ovarian cancer. For the majority of patients, pleural effusion occurs in the lung on the same side as the cancer. For one third of the patients, pleural effusion occurs in both lungs.
Pleural effusion in cancer patients can be caused by several different conditions. Blockage of the lymphatic system, a series of channels for drainage of body fluids, interferes with the removal of pleural fluid. Blockage of the veins of the lungs increases the pressure at the pleurae which causes fluid accumulation. Cancerous cells may seed onto pleurae and cause inflammation which increases fluid in the pleural space. High numbers of cancerous cells may collect in the pleural space (tumor cell suspensions) which causes extra fluid to be released. Accumulation of fluid in the abdominal cavity may cross over to the pleural space.
Management of pleural effusion strives to relieve symptoms and improve quality of life. Cure is not always possible. The treatment method depends on the patient's age, prognosis, and location of the first tumor. Treatment for patients with pleural effusion who are asymptomatic (do not have symptoms) consists solely of observation.
Treatment options for pleural effusion include:
Belinda Rowland, Ph.D.
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Author Info: Belinda Rowland Ph.D., The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Cancer, 2002 |