Read about how cancer can cause fluid to collect around the lungs or in the tummy (abdomen).
Fluid on the lungs
Two sheets of tissue protect the lungs. They are called pleural membranes (or pleura). The space inbetween the pleura is called the pleural space.
Cancer cells can inflame the pleura and this makes fluid. The fluid builds up in the pleural space and is called a pleural effusion. The fluid stops your lungs from expanding fully. So you have to take shallower breaths and make more effort to breathe.
Your doctor can put in a tube for a short time to drain the fluid and help you breathe more easily.
You can also have treatment to try to stop the fluid from building up again. This is called pleurodesis.
If your doctor talks about fluid on the lung they might mean pleural effusion. Or they might mean you have fluid actually collecting inside the lung. This is called pulmonary oedema. It is not usually possible to have this fluid drained. Pulmonary oedema is usually caused by heart problems. You might need treatment to stop the fluid collecting.
Fluid in the abdomen (ascites)
Cancer can also make fluid build up in the tummy area (abdomen). This fluid is called ascites.
Cancer cells may attach themselves to the lining of the abdomen and irritate it. This makes the abdominal lining make fluid, which collects in the abdomen.
Ascites is quite common in women with ovarian cancer. People with secondary liver cancer may also get ascites because of congestion in the liver making pressure build up in the circulation. The pressure makes fluid leak out from the bloodstream and lymphatic system and collect in the abdomen.
If there is a lot of fluid, your abdomen can become quite swollen. So it pushes upwards, against your stomach and the sheet of muscle that separates your abdomen from your chest (the diaphragm).
The increased pressure on your diaphragm makes it harder for your lungs to expand when you breathe in. This can make you breathless.