Primary adenocarcinoma of the lung - histological subtypes and outcome after surgery, using the IASLC/ATS/ERS classification of lung adenocarcinoma

Adenocarcinoma is the most common histological type of lung carcinoma. Recently the histologic classification of adenocarcinomas in the lung was modified to better reflect biologic properties and prognosis. We reviewed the histology of all primary lung adenocarcinomas operated on in Iceland during a 20-year period and assessed the impact of histology on survival. This nationwide study included 285 patients (mean age 67 years, 57% female), who underwent resection in Iceland from 1991 to 2010. Tumors were reclassified according to the current IASLC/ATS/ERS classification system. Overall survival was estimated by the Kaplan-Meier method and Cox regression analysis used to evaluate prognostic factors of overall mortality. Acinar predominant adenocarcinoma was the most common histological subtype (46%) followed by solid-predominant (SPA) with mucin production comprised (23%). Non-invasive carcinomas were rare. A difference in survival between the histological adenocarcinoma subtypes was not seen (p = 0.32) and multivariate analysis showed that advanced stage and age predicted worse outcome, but histologic subtyping of adenocarcinoma did not. In this nation-wide study there was not a statistical difference in survival according to adenocarcinoma subtypes and the histological subtype did not predict mortality. Preinvasive and minimally invasive adenocarcinomas were rare.