Shortness of breath
Shortness of breath in malignant mesothelioma may arise for various reasons. Many patients develop a pleural effusion with malignant mesothelioma; this fluid collection prevents the lung inflating fully on the affected side. If the tumor extends directly into the lung tissue, breathing difficulties can occur. In addition, around 20% of patients with pleural malignant mesothelioma also have asbestosis (replacement of lung tissue with fibrous tissue), another cause of breathlessness in those exposed to asbestos.

Pleural effusions tend to persist in malignant mesothelioma once they have developed. The can be drained by thoracentesis (insertion of a needle between the ribs and into the pleural space), but they usually return rapidly after this. Repeat thoracentesis is not helpful and diuretics (medications that promote loss of fluid from the body) do not prevent re-accumulation of fluid.

The two layers of the pleura can be fused together by to prevent a further collection forming, in a procedure known as pleurodesis. With pleurodesis, a substance is injected into the pleural space via a chest tube placed between the ribs, which then causes the lung and its overlying visceral pleura to adhere to the parietal pleura lining the chest wall. The procedure requires that the lung is inflated enough to allow it adhere to the parietal pleura; this may be difficult in malignant mesothelioma if there is a thick rind of tumor preventing the lung from expanding fully. In such cases, patients may be referred for pleurectomy instead.

An alternative to pleurodesis and pleurectomy in patients who are suitable for these procedures is the placement of a pleuroperitoneal shunt. This drains the fluid from the pleural effusion into the abdominal cavity, with the aim of allowing the patient to breathe more easily.

Radiation therapy has also been used to reduce pleural effusions.

When breathlessness persists, it is often managed symptomatically with opioid drugs and supplemental oxygen therapy.