Pleural effusions are a buildup of fluid within the chest cavity, outside the lungs.
Up to 95% of pleural mesothelioma patients have pleural effusions.
The buildup of fluid may cause patients to experience breathing difficulties.
Pleural effusions may be treated by removing the fluid from the pleural cavity.
Pleural effusions are a common diagnosis in the United States and generally indicate a larger condition or disease. For pleural mesothelioma patients, pleural effusions develop in the majority of cases, especially among patients with late-stage disease. While a pleural effusion may be a symptom of pleural mesothelioma itself, the condition can also cause its own symptoms like breathlessness. The optimal treatment for pleural effusions depends on the patient and disease-related factors.
What Is a Pleural Effusion?
Pleural effusions are a buildup of pleural fluid within the pleural space. There is typically 10 – 20 mL of fluid between the lining of the lungs and chest wall to facilitate movement of the lungs when breathing. An effusion occurs when too much of this fluid accumulates in the area. If left untreated, the weight and volume of the fluid may prevent the lungs from properly expanding and cause patients to feel breathless.
Pleural effusions may occur as a result of mesothelioma and other types of cancer, cancer treatments or other medical conditions. When caused by cancer, pleural effusions are exudative. Non-cancerous pleural effusions are considered transudative. Almost 50% of cancer patients whose cancer has metastasized, or spread from where it first formed, will experience exudative pleural effusions.
Symptoms of Pleural Effusions
The most common symptom of pleural effusions is dyspnea, or shortness of breath. Studies show about 30% of pleural mesothelioma patients experience dyspnea as a result of pleural effusion.
Symptoms of Pleural Effusions
- Dry Cough
- Dyspnea (shortness of breath)
- Dull chest pain
The presenting symptoms may also be tied directly to the underlying cause of the fluid buildup. For example, even without pleural effusions, many pleural mesothelioma patients will experience a persistent cough and shortness of breath because the disease impacts the lungs. As such, pleural mesothelioma patients with pleural effusions may face a variety of symptoms.
In some cases, the pleural effusion may be asymptomatic.
Diagnosing Pleural Effusions
Treatment for pleural effusions varies depending on if the effusion is malignant or benign, so accurate diagnosis is imperative. Risk factors for developing malignant pleural effusions caused by mesothelioma include:
- Advanced age
- A history of smoking
- Exposure to asbestos
- Weight loss
Physicians will ask the patients about these risk factors while conducting tests for an accurate diagnosis. The diagnostic process begins with imaging tests of the chest. These scans commonly include X-rays and CT scans, and may include positron emission tomography (PET) or magnetic resonance imaging (MRI) scans in rare cases. An upright chest X-ray is the optimal scan if available.
The presence of pleural thickening, or scarring of the lung linings, on these scans is suggestive of malignant effusions. Scans that show 1 cm or greater of pleural thickening tend to be malignant in nature, which will lead to the doctor performing further diagnostic testing to determine the cause of the malignant effusion. It is also typical for a physical exam to accompany the diagnostic testing. A physician will listen for a dull sound when knocking on the chest. While these tests can aid diagnosis, the only way to definitively diagnose a pleural effusion as either malignant or benign is through either analysis of the pleural fluid after a biopsy, which can include a thoracentesis or tissue sample.
Pleural effusion samples are sent to a lab for microscopic inspection, including tests for total protein, cell count and cell differential. Exudative effusions, including those in mesothelioma cases, tend to have more protein in the fluid. Examining the structure and appearance of any cells found in the fluid is known as cytology, and may yield the diagnosis of mesothelioma. However, cytology of the effusion may be mistakenly read as negative in cases of pleural mesothelioma, if there are few cells harbored in the fluid collected.
If patients and physicians opt for a tissue biopsy, a CT-guided biopsy has been found to be most effective. Biopsies completed using the imaging scan to guide retrieval of a tissue sample had a much higher sensitivity for malignant pleural effusions than those without guidance. The CT-guided biopsies resulted in 87% sensitivity, compared to a 47% sensitivity among closed biopsies. This heightened sensitivity results in more accurate diagnoses, which leads to proper treatment.
Prognosis for Mesothelioma Pleural Effusions
Mesothelioma patients with pleural effusions tend to have a less favorable prognosis than those without the condition. As the mesothelioma cancer becomes more advanced, the cancer can overtake the pleural space and prevent the accumulation of fluids. Though pleural effusion would no longer be a prognostic factor for these patients, prognosis would still be poor overall, with many patients living about one year or less.
Prognosis for mesothelioma patients, with or without pleural effusions, is also impacted by:
- Age of the patient
- Cell type
- Overall health
For patients who are able to undergo treatment for mesothelioma and the pleural effusion itself, prognosis can widely vary. Patients whose pleural effusion is diagnosed early tend to respond better to treatment and are less likely to experience recurrence, which can negatively impact prognosis. Unfortunately, exudative effusions, like those caused by mesothelioma, are most likely to return. The recurrence risk is especially great in mesothelioma patients with effusions whose cancer has metastasized into the lymph nodes.
One study of 278 patients with different types of cancer and pleural effusions found patients had a median survival of seven months following palliative treatment for the effusion. Participants in the study diagnosed with malignant mesothelioma specifically survived 9.9 months after their diagnosis with pleural effusions.
Treating Pleural Effusions
Treatment plans for pleural effusions are typically focused on palliative care for symptom management in the hopes of improving a patient’s overall quality of life, as well as possibly extending life expectancy. Treatment options vary according to the patient’s health and their overall mesothelioma treatment plan.
Treatment for the pleural effusion also varies according to how much fluid has accumulated within the pleural space. Those with less than 10 millimeters of fluid are often treated with a diuretic, while patients experiencing a greater amount of fluid buildup require a more invasive treatment.
For patients with more than 10 millimeters of pleural fluid, the most common treatment is a thoracentesis or pleurocentesis. The removal of fluid is used as a palliative treatment option to relieve patient discomfort. The fluid within the chest cavity often causes pressure in the chest and difficulty breathing. The thoracentesis uses an ultrasound to minimize risk of complications, such as perforating the lung. Researchers have found, however, that the efficacy of the treatment is often temporary and the pleural effusion commonly recurs. Treatment may be repeated as necessary, but with each additional thoracentesis procedure, the risks of complications increase.
Risks of Thoracentesis
- Collapsed lung
- Low blood pressure
For eligible patients, a pleurodesis may be beneficial for a more long-term solution. The procedure closes the pleural space, eliminating the chance of pleural fluid accumulation. After a thoracentesis is performed, which removes the excess fluid, a drug is inserted to cause inflammation of the two walls of the pleural cavity. The drugs used to cause this irritation and resulting inflammation are called sclerosing agents. The most commonly used materials are talc and doxycycline. Studies have found a talc pleurodesis is successful in 60 – 80% of patients.
More invasive thoracic surgical procedures may also be used to remove the excess pleural fluid and prevent future accumulation. The surgical placement of a shunt allows pleural fluid to be removed from the pleural space and moved into the peritoneal cavity, allowing for easier removal. However, in some cases, the abdominal fluid may be absorbed back into the body, which eliminates the need for further intervention. After a shunt is placed, the patient can press on a pump to move the fluid from the pleural cavity to the abdomen. Patients typically use the pump several times a day. More commonly, patients with refractory pleural effusions are offered an indwelling, tunneled pleural catheter that can be drained at home, which minimizes the number of trips to the physician/hospital and thoracentesis procedures required.
Not uncommonly, pleural mesothelioma results in an effusion, but the disease remains confined to one side of the chest. In this situation, patients may still be considered for surgical resection of the tumor, depending on the rest of the evaluation.
Prompt treatment of pleural effusions, and their underlying cause, can increase patient survival rates. Those who have experienced asbestos exposure should seek medical attention and discuss their risk of developing mesothelioma cancer and its related symptoms, like pleural effusions.