Clear cell adenocarcinoma of the lung: a SEER analysis

Clear cell adenocarcinoma (CCA) in lung has been considered as a rare subtype of lung adenocarcinoma. However, recent classifications of lung adenocarcinoma proposed to discontinue CCA due to lack of available data with clinical significance. Patients with CCA and lung adenocarcinoma not otherwise specified (LANOS) were queried from The Surveillance, Epidemiology, and End Results Program (SEER) database. Cancer-specific survival was studied according to gender (male, female), age (0-69, 70+), SEER specific stage A system (localized, regional and distant), year of diagnosis (1973-2000, 2001-2013), surgery (yes, no), and radiation therapy (yes, no) using Kaplan-Meier curves. Multivariate analysis was used to study independent predictors of cancer-specific survival. A total of 1,227 and 233,154 patients with the diagnosis of CCA and LANOS respectively were found in the SEER database. CCA histology was significantly associated with an early year of diagnosis, younger age, early stage, surgery, and lack of radiation. Kaplan-Meier curves showed that patients with CCA histology had significantly better cancer-specific survival (P<0.0001, Log-Rank). Subset analysis demonstrated the difference in cancer-specific survival between CCA and NOS histology was significant in localized and regional but not distant stage disease (P=0.0453, 0.0009, 0.0664, respectively). Patients with CCA histology have superior survival in the locoregional stage according to our SEER analysis, suggesting its unique role in prognosis despite it being removed from recent pathologic classifications.