Survival comparison of adenosquamous, squamous cell, and adenocarcinoma of the lung after lobectomy

Background: Primary adenosquamous carcinoma (ASC) of the lung is a rare tumor that may carry a poor prognosis. We examined a national database to see if ASC exhibited distinct clinical behavior from squamous cell (SC) and adenocarcinoma (AC) of the lung. Methods: This is a retrospective study querying the Surveillance, Epidemiology, and End Results database to identify 872 surgical patients diagnosed with ASC, 7888 with SC, and 12,601 with AC of the lung from 1998 to 2002. Analysis characterized clinical variables to determine patterns of presentation and compared survival among the above three histologic groups after lobectomy for stage I and II disease. Results: ASC represented 4.1% of the 21,361 patients examined. ASC tended toward right side (56.9%) laterality and upper lobe (60.0%) location. Compared with AC, patients with ASC and SC were more likely to be male (p < 0.0001), and ASC patients had worse histologic grade (p< 0.0001). Survival after lobectomy for stage I and II disease was significantly reduced in ASC and SC compared with AC (p < 0.0001). ASC had a significantly increased hazard ratio of 1.35 and 1.27 relative to AC and SC, respectively. Other significant negative predictors of survival included tumor grade of III and IV, stage II, age, and black ethnicity. Conclusions: This large review demonstrates that ASC is an uncommon tumor with distinct clinical behavior and worse prognosis than AC and SC. Further insight into the molecular profile of ASC is needed to determine the cause of its biologic aggressiveness.