Korean laboratory medicine experts developed consensus recommendations for testing circulating tumour DNA in pleural effusion and bronchoalveolar lavage fluid, sources that sit close to the tumour and can carry more tumour DNA than blood. The process combined a review of 27 studies, a national survey of 109 laboratories and clinicians, and a two-round Delphi panel of eight experts.
Fifteen recommendations cover sample collection and handling, analytical validation and quality control, and how results should be reported and used. Most of the evidence came from pleural effusion, with far fewer lavage studies. Only about a fifth of survey respondents were already using these samples, held back by missing protocols, reimbursement and technical difficulty.
For oncologists, the practical message is that a pleural effusion already being drained can be a molecular sample when tissue is scarce, provided the laboratory handles it to a standard. Lavage-based testing is less established.
- When tissue is insufficient for molecular testing, consider whether drained pleural fluid could be sent for ctDNA analysis.
- Agree handling and transport standards with the laboratory before sending fluid samples.
- Interpret a negative fluid ctDNA result cautiously and consider re-biopsy.
- Evidence for lavage fluid is thinner than for pleural effusion.
Why it matters
Many patients with advanced lung cancer have an effusion drained anyway, and it can spare a further biopsy.
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Consensus recommendations from eight experts in one country, built on mostly pleural-fluid studies.
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