Riken Kawachi, MD and colleagues said that the efficacy of screening for lung cancers still remains controversial, and none of the guidelines for lung cancer detection recommend screening for lung cancers. They undertook the study to retrospectively characterize and analyze the clinicopathological features of screen detected (SCR) lung cancer in comparison with lung cancers detected by other means.

A retrospective analysis of the records of 2,281 patients who underwent lung resection for primary lung cancer was done by the researchers between 2000 and 2006. They classified patients into three groups, according to the method of detection: SCR (1,290), symptom-detected (SYM = 481) and incidental (INC = 568). In the SCR group, clinicopathological factors they analyzed according to the detection modality: chest x-ray (82.6 percent), CT (13.9 percent), PET (1.6 percent) and sputum cytology (1.3 percent).

Kawachi and colleagues found that the percentages of smaller (less than 2 cm) lung cancer (SCR, 42.6 percent; SYM, 19.6 percent; INC, 40.9 percent), adenocarcinoma (SCR, 85.8 percent; SYM, 58.6 percent; INC, 73.1 percent) and pathologic stage I (SCR, 73 percent; SYM, 47 percent; INC, 71.2 percent) were higher in the SCR group than in the other two groups.

The investigators found that the five-year survival rates in SCR, SYM and INC group were 79.6 percent, 74.6 percent and 64.6 percent, respectively. The patients with CT detected lung cancer had a higher incidence of smaller size (less than 2 cm, 76.4 percent), adenocarcinoma (92.6 percent) and stage I (clinical: 97.2 percent, pathologic: 93.1 percent).

However, they also reported that the five-year survival rates in the CT and chest x-ray groups were 91.2 percent, and 77.8 percent respectively.

Kawachi and colleagues noted that SCR lung cancers were characteristically less advanced, were more frequently adenocarcinoma histologically and had a smaller diameter.