Histo-cytological diagnostic accuracy in lung cancer

Objective The majority of patients with lung cancer are treated on the basis of a diagnosis made from the analysis of a small tumour biopsy or a cytological sample and histotype is becoming a critical variable in clinical workup as it has led to the introduction of newer biologically targeted therapies. Consequently, simply classifying cancers as small cell lung cancers or non‐small cell lung cancers is no longer sufficient. Methods From 2009 to 2011, a review of the histo‐cytological database was conducted to identify all small biopsy and cytology specimens collected for diagnostic purposes in patients with a thoracic lesion. In total, 941 patients were studied by examining exfoliative and/or aspirative cytological samples. To establish the accuracy of these methods, cytological and biopsy diagnoses were compared with each other and with subsequent resection specimens when available. Moreover, during the diagnostic workup, we examined a validated panel of immunohistochemical markers. Results The diagnostic concordance of pre‐operative diagnoses with surgical samples was high in both cytology and biopsy samples [κ = 0.71, confidence interval (CI) = 0.6–0.81; P