How many names for a rose: Inconsistent classification of multiple foci of lung cancer due to ambiguous rules

ObjectivesStage 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 methodsWe 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.ResultsWe 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.ConclusionThe marked variability in classification must be taken into account when interpreting reported outcomes of patients with multiple pulmonary foci of lung cancer.