Objectives: Stage classification is important because it allows consistent definition of patient groups, and thus provides a foundation for comparison of outcomes. For patients with multiple pulmonary foci of lung cancer, however, the classification rules are ambiguous and confusing.
Materials and methods: We surveyed experts and clinicians who regularly evaluate patients with lung cancer to see how similar or different their interpretation of the official stage classification was for such patients.
Results: We found a great deal of inconsistency in how four clinical scenarios were classified. No method of classification was chosen by a majority when there were more than two choices allowed by the classification rules. In a scenario with pulmonary foci of cancer of different histologic types, 86% classified this as separate primary cancers and 14% as multifocal lung cancer.
Conclusion: The marked variability in classification must be taken into account when interpreting reported outcomes of patients with multiple pulmonary foci of lung cancer.
Keywords: Adenocarcinoma; Lung cancer; Multi foci; Non-small cell lung cancer; Stage classification; TNM.
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