Overview

Malignant pleural effusion (MPE) occurs when tumour cells involve the pleural space — either by direct invasion, haematogenous seeding, or lymphatic obstruction. It is the second most common cause of exudative pleural effusion after parapneumonic effusion. MPE indicates advanced disease and significantly impacts quality of life through progressive dyspnoea.

Aetiology

Lung cancer and breast cancer together account for approximately 50–60% of all MPEs. Other common primary sites include ovary, stomach, and lymphoma.

Common primary tumours associated with MPE
Most commonLung cancer (35–40%) · Breast cancer (20–25%)
Other frequentOvarian cancer · Gastric cancer · Lymphoma
Unknown primary~7% — MPE is the presenting feature before primary is identified
Pseudo-MPEMeig's syndrome (ovarian fibroma + ascites + effusion) — benign; resolves with tumour excision

Diagnosis

MPE is an exudate by Light's criteria. The effusion is typically haemorrhagic or serosanguinous. Positive cytology on pleural fluid confirms the diagnosis in 60–70% — sensitivity increases with second sample. If cytology is negative and malignancy is strongly suspected, thoracoscopy-guided pleural biopsy provides near-100% diagnostic yield and simultaneous assessment for pleurodesis.

  • CT thorax: identifies pleural thickening, nodularity, loculations, and primary tumour if not yet diagnosed
  • PET-CT: useful for identifying the primary and assessing extent of systemic disease
  • Thoracoscopy: gold standard for diagnosis when fluid cytology is negative — visual inspection of pleura, targeted biopsy, and talc poudrage pleurodesis at same sitting
Key principle — trapped lung

Before committing to pleurodesis, confirm the lung re-expands fully after drainage. If the lung is trapped by tumour encasement (visceral pleural coating), the pleural space cannot be obliterated and pleurodesis will fail. In trapped lung, an indwelling pleural catheter (IPC) is the preferred long-term drainage strategy.

Management

Management options for malignant pleural effusion
OptionIndicationNotes
ObservationSmall, asymptomatic effusionMonitor; treat underlying malignancy
Therapeutic thoracentesisSymptomatic; assessment of lung re-expansionTemporary relief; high recurrence rate; repeated procedures increase risk
Indwelling pleural catheter (IPC)Symptomatic effusion; trapped lung; patient preference for outpatient managementPatient-controlled drainage; spontaneous pleurodesis in ~50% after 6–8 weeks; preferred in short prognosis
Talc pleurodesis (via drain or thoracoscopy)Expandable lung; reasonable performance status; prognosis >3 monthsTalc poudrage via thoracoscope has highest success rate (~80%); slurry via chest tube ~60–70%
Thoracoscopic pleurectomy / abrasionFailed chemical pleurodesisReserved for good PS patients; mechanical pleurodesis
Pleuroperitoneal shuntTrapped lung; failed pleurodesis; poor surgical riskPatient-pumped valve; useful in selected cases
IPC vs talc pleurodesis — current evidence

The TIME2 trial and subsequent studies show IPC and talc pleurodesis are equivalent in symptom control. IPC requires fewer hospitalisations and is preferred for patients with trapped lung or short prognosis. Spontaneous pleurodesis occurs in ~50% of IPC patients, potentially avoiding further procedures. The choice should be individualised based on lung expandability, prognosis, patient preference, and local expertise.

Systemic therapy

Many MPEs respond to treatment of the primary tumour — particularly lymphoma (radiotherapy), breast cancer, and SCLC. For current systemic therapy recommendations, refer to tumour-specific guidelines from ESMO or NCCN.

Further reading

All clinical content should be verified against current guidelines before clinical application. This resource is intended for revision and educational purposes only.

Standard textbooks

  • Shields TW, LoCicero J, Reed CE, Feins RH. General Thoracic Surgery. 7th ed. Lippincott Williams & Wilkins.
  • Sellke FW, del Nido PJ, Swanson SJ. Sabiston & Spencer Surgery of the Chest. 9th ed. Elsevier.
  • Pearson FG, et al. Thoracic Surgery. 3rd ed. Churchill Livingstone.

Current guidelines & resources