Clinicopathological characteristics of screen-detected lung cancers

Background: The efficacy of screening for lung cancers remains controversial, and none of the guidelines for lung cancer detection recommend screening for lung cancers. The purpose of the present study was to retrospectively analyze and characterize the clinicopathological features of screen-detected (SCR) lung cancer in comparison with lung cancers detected by other means. Patients: The records of 2281 patients who underwent lung resection for primary lung cancer between 2000 and 2006 were analyzed retrospectively. Patients were classified into three groups according to the method of detection: SCR (n =1290), symptom-detected (SYM, n =481), and incidental (INC, n =568). In the SCR group, clinicopathological factors were analyzed according to the detection modality: chest x-ray (n =1136, 82.6%), computed tomography (CT, n =196, 13.9%), positron emission tomography (n =22, 1.6%), and sputum cytology (n =17, 1.3%). Results: The percentages of smaller (≤2 cm) lung cancer (42.6%: SCR, 19.6%: SYM, 40.9%: INC), adenocarcinoma (85.8%: SCR, 58.6%: SYM, 73.1%: INC), and pathologic stage I (73.0%: SCR,47.0%: SYM, 71.2%: INC) were higher in the SCR group than in the other two groups. The 5-year survival rates in SCR, SYM, and INC group were 79.6%, 74.6%, and 64.6%, respectively. The patients with CT-detected lung cancer had a higher incidence of smaller size (≤2 cm, 76.4%), adenocarcinoma (92.6%), and stage I (clinical: 97.2%, pathologic: 93.1%). The 5-year survival rates in the chest x-ray and CT groups were 77.8% and 91.2%, respectively. Conclusions: SCR lung cancers were characteristically less advanced, had a smaller diameter, and were more frequently adenocarcinoma histologically. CT-screening may be able to detect early stage lung cancers, and improve the prognosis of lung cancer patients.