Malignant Pleural Effusion Treatment and Outlook

A malignant pleural effusion is a common but serious complication of cancer in which fluid collects between the membranes lining the lungs, called the pleura. It occurs in between 7% and 23% of lung cancers but can also occur with breast cancers, lymphomas, and other malignancies (cancers).

In all, malignant pleural effusion affects around 15% of people with cancer and is generally associated with a poor outlook. Symptoms include difficulty breathing, chest pressure, and an inability to lie flat. The various treatments are focused on removing the fluids either directly or indirectly.

The article describes the symptoms and causes of malignant pleural effusion, including how it is diagnosed and treated. It also explains the impact malignant pleural infusion has on survival.

What Are the Characteristics of Malignant Pleural Effusion?

The symptoms of malignant pleural effusion vary by the extent of fluid infiltration. The effusion may be large and diffuse or involve a small portion of the pleural space. The effusion may be limited to one area, or there may be several areas of effusion (called septated pleural effusions). The condition can also be bilateral (affecting both lungs) or unilateral (affecting only one lung).

A malignant pleural effusion is recognized by the following signs and symptoms:

• Shortness of breath
• Dry cough that worsens when leaning forward or lying on your side
• Chest pain
• A feeling of chest pressure or heaviness
• Low exercise tolerance
• Inability to lie flat without feeling like you are suffocating

What Stages Does Malignant Pleural Effusion Occur?

Malignant pleural effusion is caused either by a cancerous tumor originating in the pleura or by cancer in another part of the body that has metastasized (spread) to the pleura.

Almost all metastatic cancers can invade the pleura and cause a malignant pleura effusion. Lung cancer is the most common cause, accounting for one-third of all cases, followed by breast cancer, lymphoma, and mesothelioma. Other cancers like ovarian cancer and leukemia can also cause pleural effusion.

Malignant pleural effusion most often occurs with advanced stage 4 (metastatic) cancer. However, with lung cancer, it can sometimes occur before stage 4 and be the very first sign of cancer.

Similarly, pleural effusion can occur at any stage of lymphoma. This is because lymphoma is not a solid tumor cancer but one that spreads through fluids and vessels of the lymphatic system. While nearly half of all pleural effusions occur with stage 4 lymphoma, the rest are distributed almost equally among stages 1, 2, and 3.

With solid tumors, malignant pleural effusion is caused by the leakage of fluids from newly formed blood vessels that "feed" these tumors and help them grow. The formation of new blood vessels (called angiogenesis) also triggers the release of inflammatory compounds that promote vascular permeability (leakage), allowing fluids to flow into the pleural space.

A pleural effusion may also be caused by treatments for lung cancer, such as surgery, radiation therapy, or chemotherapy.

How Malignant Pleural Effusion Is Diagnosed

A malignant pleural effusion is often first suspected because of symptoms or findings on a chest X-ray or computed tomography (CT) scan.

If your doctor suspects a malignant pleural effusion, the next step is usually a ​thoracentesis. This is a procedure in which a needle is inserted through the chest wall into the pleural space to get a sample of fluid. This fluid is then examined under a microscope to see if cancer cells are present.

If a thoracentesis cannot be done, or if the results are inconclusive, a pleuroscopy may be ordered. This is a more invasive procedure in which a scope is inserted into the chest through an incision to access the pleural space.

How Is Malignant Pleural Effusion Treated?

Because pleural effusion usually occurs with stage 4 disease, the aim is not to cure the cancer but rather to manage symptoms and improve the person's quality of life (known as palliative or comfort care).

Thoracentesis

Thoracentesis can not only diagnose malignant pleural effusion but also remove accumulated fluid caused by the effusion. While effective, effusions frequently return and often require retreatment to keep the fluids under control.

Although thoracentesis is generally safe, complications such as infection, pneumothorax (a collapsed lung), chest wall bleeding, blood clots, and pulmonary edema ("water in the lungs") are possible.

Pleurodesis

Another procedure that works in roughly 60% to 90% of cases is pleurodesis. In this procedure, a tube is inserted into the pleural space, and a substance (commonly talc) is injected between the membranes. The chemicals trigger inflammation which causes the two linings to stick together and effectively press the fluid out of the pleural space.

The complications of pleurodesis are similar to those of thoracentesis.

Indwelling Pleural Catheters

Another procedure used for a malignant pleural effusion is an indwelling pleural catheter (IPC). In this procedure, a small tube (catheter) is inserted into the pleural space via an incision between the ribs. The end of the tube is attached to a replaceable vacuum container that draws out and collects the fluid.

An IPC is effective if the effusion is bilateral or there are large volumes of fluid. The procedure is often considered less invasive than pleurodesis and is effective in over 80% of cases. Many researchers feel that IPCs should be ​the first-line option for all people with malignant pleural effusion.​​

An IPC may cause infection in less than 5% of users. A larger concern is the long-term risk of metastasis caused by the spread of cancer cells via the catheter.

Additional Treatment Options

If a malignant pleural effusion persists despite these treatments, surgery may be used to drain the fluid into the abdomen, or a pleurectomy may be performed to remove part of the pleura.

Chemotherapy may help with malignant pleural effusions due to small cell lung cancer but is not usually very effective with non-small cell lung cancer.

How Long Can Someone Live With Malignant Pleural Effusion?

The occurrence of malignant pleural effusion is generally a sign of poorer outcomes. With lung cancer, the average life expectancy is less than six months, while the median survival time (the time during which 50% of people will have died) is four months.

When all cancer types are factored in, the median survival can be anywhere from three to 12 months. The only exception is pleura effusion with ovarian cancer, which has a median survival time of 21 months.

Summary

Malignant pleural effusion is a complication of cancer that causes the build-up of fluid in the membrane surrounding the lungs. It most often occurs with advanced stage 4 cancer, including lung and breast cancer. Symptoms include shortness of breath and chest pain or pressure.

Malignant pleural effusion is usually a sign of a poorer outcome and shortened life expectancy. Treatments can help control the complication, including indwelling catheters which drain fluid from the pleural space, or pleurodesis which uses chemicals to press fluids out of the pleural space.