A recent study found no link between mesothelioma survival and exposure to pleural fluid. But that does not necessarily mean the link doesn’t exist.
Pleural fluid is also called pleural effusions or “water on the lungs”. It is extra fluid that builds up around the lungs. It is common in people with heart failure, kidney or liver disease, pleural mesothelioma and some other kinds of cancer.
Pleural effusions are usually treated as an uncomfortable mesothelioma symptom. Draining the fluid can help patients breathe easier.
But researchers at Oxford University wondered whether the pleural fluid itself could shorten mesothelioma survival. In this study, the answer appears to be no. But the researchers warn this may not be the final word on the topic.
What Causes Pleural Effusion and What Does it Do?
Malignant pleural mesothelioma is a cancer that occurs on the pleura, a thin membrane that surrounds the lungs. This membrane has several layers. There is normally a small amount of fluid between these layers. This lets the lungs move naturally inside the chest.
As the body tries to fight a mesothelioma tumor, it may produce too much fluid. When the fluid has nowhere to go, it accumulates between the pleural layers.
Pleural fluid in the space between the pleura and the lungs makes it harder for the lungs to expand. Breathing problems are the first sign of pleural mesothelioma for many patients. It is often because of this excess pleural fluid.
Removing some of the fluid with a needle or a catheter is one way to help patients feel better. Doctors can also close off the pleural space chemically or surgically. This way, no more pleural fluid can collect there. This process is called pleurodesis.
Measuring the Risk of Pleural Fluid
Mesothelioma is a fast-growing and deadly cancer. But doctors do not usually think of the pleural effusion as dangerous by itself.
To find out, Oxford researchers analyzed data from 761 mesothelioma patients at three UK hospitals. The patients were diagnosed between 2008 and 2018.
The researchers looked at medical images to see how much effusion each patient had and for how long. Taking into account other factors that impact mesothelioma survival, they compared the length of time that a person was exposed to pleural fluid with how long they lived.
The median mesothelioma survival for all patients in the study was 278 days. People who had pleurodesis did live longer. They had a median survival of 473 days. But there was no proof that this had anything to do with exposure to the fluid itself.
“Pleural fluid exposure duration showed no association with survival,” reports lead author and lung cancer researcher Rachelle Asciak. “However, it is unclear whether duration of MPM exposure to pleural fluid is associated with survival within the limitations of this retrospective study.”
The research team says prospective studies are the only way to know for sure if pleural fluid exposure is dangerous. A prospective study is a study that watches for outcomes. A retrospective study analyzes past data.
Asciak, R, et al, “The association between pleural fluid exposure and survival in pleural mesothelioma”, June 10, 2021, Chest, Online ahead of print, https://journal.chestnet.org/article/S0012-3692(21)01104-1/pdf