Malignant pericardial effusions occur in less than 5% of patients with cancer, and are most commonly due to malignant infiltration; other causes include radiotherapy, uremia and infection (see Table).
Cancer can involve the pericardium by direct extension, retrograde lymphatic infiltration or haematogenous spread.
Lymphatic obstruction in the mediastinum can also lead to the development of a pericardial effusion.
Lung and breast cancers and the haematological malignancies account for three quarters of malignant pericardial effusions.
Radiotherapy may cause pericardial effusion either as an acute (weeks/months) or late (years) adverse effect; the latter is often accompanied by signs of pericardial constriction.
- Malignant infiltration
- Mediastinal lymphatic obstruction
late pericardial effusion ± constriction
The clinical features depend on the volume of pericardial fluid, the rate of accumulation, and the underlying cardiac function. The pericardium normally contains less than 50 ml of fluid, but may accommodate several hundred millilitres if the accumulation is slow. If the increase is rapid, serious symptoms and signs can develop with small changes in the pericardial fluid volume. Pericardial tamponade exists when the amount of fluid present is sufficient to cause significant impairment of cardiac function.
Woodruff R. Palliative medicine evidence-based symptomatic and supportive care for patients with advanced cancer. Fourth edition. Oxford University Press, 2004. (p. 300)