Pleural Effusion Staging — SCE Medical Oncology MCQ

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EasyLung CancerPleural Effusion StagingSCE Medical Oncology

A 55-year-old man with metastatic NSCLC develops a malignant pleural effusion. Thoracentesis confirms adenocarcinoma. This changes his staging from M1a to what TNM classification?

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Correct answer: D — M1a — malignant pleural effusion is classified as M1a (intrathoracic dissemination) in the TNM 8th edition, not M1b or M1c

In TNM 8th edition for lung cancer, malignant pleural (or pericardial) effusion and contralateral/bilateral lung nodules are classified as M1a (intrathoracic dissemination). M1b is a single extrathoracic metastasis. M1c is multiple extrathoracic metastases (one or more organs). The M1a subclassification is important because patients with malignant pleural effusion as their only site of metastatic disease have a relatively better prognosis than M1b/c and may benefit from more aggressive treatment approaches.

Reference: NICE NG122; IASLC TNM 8th Edition; ESMO 2024 NSCLC