During the 1-year period from January 2012 to December 2012, we conducted a retrospective, single-center population-based screening program for lung cancer in the setting of annual medical examinations. Participants were asymptomatic adults without prior history of any cancer. Low-dose CT and chest radiography were offered to all individuals. Baseline CT evaluations were defined as positive if any noncalcified nodule ≥ 4 mm in diameter, which were then classified as solid, pure ground-glass or partial ground-glass opacity.
Of 3339 individuals, we detected 34 cancers, yielding an overall cancer detection rate of 1.02%. There was a particularly high cancer detection rate of 6.2% (8/129) in the high-risk group aged younger than 50 years with a positive family history of all types of cancers in first-degree relatives. Adenocarcinomas accounted for 88% (30/34) of cancers and 99% of them were early-stage (including carcinoma in situ and Stage I). The probability of cancers was significant higher in nodules with interval growth (odds ratio 257.89, p = 0.0002). There was no significant difference in the probability of cancers between ground glass opacity nodules and solid nodules (odds ratio 1.16, p = 0.72). Of all screen-detected cancers, 61.76% (21/34) were chest radiographically occult.
Low-dose CT is effective to detect early lung cancers. Further establishment of selection criteria for lung cancer screening, specifically for Asian individuals, is definitely warranted.