Fluid Around the Lungs or Malignant Pleural Effusion

Approved by the Cancer.Net Editorial Board, 09/2021

A build-up of fluid in the space between the lungs and the chest wall is called a "pleural effusion." This area of the body is called the pleural space.

Pleura is another word for membrane. You have pleura surrounding your lungs and lining the inside of your chest. A small amount of fluid in this area is normal. It helps the lungs move in your chest as you breathe. But cancer and other conditions can cause fluid to build up. A pleural effusion can be serious and potentially life-threatening, but it is treatable.

If cancer grows in the pleural space, it causes a "malignant pleural effusion." This condition is a sign that the cancer has spread, or metastasized, to other areas of the body.

What are symptoms of a pleural effusion?

A pleural effusion can cause uncomfortable side effects. You may experience the following symptoms:

  • Shortness of breath

  • Dry cough

  • Pain

  • Feeling of chest heaviness or tightness

  • Inability to lie flat

  • Inability to exercise

  • Generally feeling unwell

Tell your health care team if you experience any of the above symptoms. Relieving side effects is an important part of cancer care and treatment. This is called palliative care or supportive care. It can help people with any stage of cancer feel better.

What causes a pleural effusion?

There are several different causes of pleural effusion. For people with cancer, pleural effusions are often malignant (see above). This means that there are cancer cells in the pleural space causing fluid to build up. Sometimes, a pleural effusion can occur as a result of inflammation, lung obstruction, trauma, or another medical condition that may not be due to cancer.

Certain types of cancer. Some types of cancer are more likely to cause a pleural effusion. For example, around 40% of people with lung cancer develop a pleural effusion at some point during the course of their cancer.

  • Breast cancer

  • Lung cancer

  • Lymphoma

  • Mesothelioma

  • Ovarian cancer

Pleural effusion can also be a sign that cancer has spread to the lymph nodes.

Cancer treatments. Radiation therapy, chemotherapy, abdominal surgery, and certain medications can cause pleural effusion. Pleural effusions may also occur after lung surgery.

Other health conditions. Pleural effusion can also be caused by other conditions that are not cancer. These conditions include:

  • Blood clots in the lungs, also called pulmonary embolism

  • Heart disease or heart failure

  • Kidney disease

  • Liver disease

  • Pneumonia

  • Airway obstruction or lung collapse

  • Poor nutrition, causing low protein levels

Pleural effusion that is caused by other conditions that are not cancer are considered "non-malignant pleural effusions." The treatment for this kind of pleural effusion may be different than what is described below.

How is pleural effusion diagnosed?

Your doctor may use the following tests to locate, diagnose, or plan treatment for a pleural effusion:

  • Physical examination

  • Chest x-ray, which is a picture of the inside of your body showing fluid buildup

  • Computed tomography (CT) scan

  • Ultrasound

  • Thoracentesis, a needle removes fluid from the pleural space for testing

After the fluid is removed for testing, a pathologist will confirm if the effusion is malignant or not, meaning if there are cancer cells present in the fluid or not. This is called pleural fluid cytology. A pathologist is a doctor who specializes in interpreting laboratory tests and evaluating cells, tissues, and organs to diagnose disease.

How is a malignant pleural effusion treated?

The most common treatment is to drain the malignant pleural fluid. Chemotherapy can also prevent the effusion from returning.

Treatment for a pleural effusion can be given in a hospital or an outpatient setting. There are several methods available to remove fluid. You and your health care team will discuss the best treatment options for you.

Thoracentesis. This procedure removes the fluid from around the lungs. It can also be used to diagnose a pleural effusion. During thoracentesis, a doctor inserts a needle to remove the fluid. An ultrasound probe may be used before a thoracentesis to see if there is enough fluid to drain.

Tube thoracostomy. In this procedure, a doctor inserts a tube into your chest to drain the fluid. Typically, the chest tube stays in for a day or longer until enough of the fluid has drained. Then, a chemical is used to stick the edge of the lung to the chest wall. This treatment, called pleurodesis, decreases the chance that the fluid will return.

Catheter. Sometimes, a catheter is used to drain fluid. A catheter is a thin tube of plastic that is inserted into the pleural fluid. A tunneled pleural catheter (TPC) can also be used. This type of catheter can be left in for long periods of time for ongoing draining. At home, you or your family member use the catheter to drain the fluid into a bottle as instructed by your doctor. After time, if your body does not produce anymore pleural effusion fluid, the catheter can be removed.

Shunt. A shunt is used to bypass and divert excess fluid from one place to another. A doctor inserts the shunt during surgery.

Surgery. In some cases, surgery may be needed to look at the pleural space, get additional biopsies, and do a pleurodesis (see above). This can often be done with a minimally invasive surgical technique called video-assisted thoracoscopic surgery (VATS).

Chemotherapy. Sometimes, the treatment for pleural effusion is to treat the cancer with chemotherapy.

Questions to ask the health care team

  • Is pleural effusion a possible side effect of the cancer I have or the cancer treatment I will receive?

  • What signs of pleural effusion should I look out for?

  • If I experience signs of pleural effusion, who should I tell? How soon?

  • How can I reach that health care team member?

  • How can this pleural effusion be treated?

  • If I need surgery, how long will the surgery take?

  • What is recovery like? What are the possible side effects I may experience?

Related Resources

Getting Started With Palliative Care

More Information

American Thoracic Society: Malignant Pleural Effusions (PDF)

National Cancer Institute: Cardiopulmonary Syndromes