Histopathologic characteristics of lung adenocarcinomas with epidermal growth factor receptor mutations in the International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society lung adenocarcinoma classification.

CONTEXT: The proposed International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification of lung adenocarcinomas has been published.

OBJECTIVE: To evaluate the correlation between epidermal growth factor receptor mutations and histologic subtypes of lung adenocarcinomas according to the upcoming new classification of lung adenocarcinomas.

DESIGN: Medical records and pathologic slides were reviewed for a total of 107 surgically resected lung adenocarcinomas. All tumors were reclassified according to the predominant histologic subtype, and comprehensive histologic subtyping with semiquantitative assessment of each of the histologic subtypes in increments of 5% was performed. Correlations with epidermal growth factor receptor status were then evaluated.

RESULTS: Epidermal growth factor receptor mutations were found in 54 cases (50.5%). Epidermal growth factor receptor mutations were significantly associated with the micropapillary-predominant subtype (P  =  .02) and with the presence (any amount) of the lepidic component (P  =  .02).

CONCLUSION: The upcoming International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification of lung adenocarcinoma is relevant in that it shows a phenotype-genotype correlation. Comprehensive histologic subtyping should be recommended because of the association of particular subtypes with epidermal growth factor receptor mutations.