Results of low-dose computed tomography (LDCT) screening for early lung cancer: Prevalence in 4 690 asymptomatic participants

Objective: To report the results of low-dose computed tomography (LDCT) screening for early lung cancer in 4 690 asymptomatic participants at the Cancer Hospital, Chinese Academy of Medical Sciences between July 2007 and June 2012. Methods: After informed consent and questionnaire forms were obtained, 4690 asymptomatic participants ≥40 years underwent chest low dose spiral CT scanning. According to the National Comprehensive Cancer Network (NCCN) guideline for lung cancer screening (version 1.1, 2012), all participants were assigned to three groups, namely high-risk, moderaterisk and low-risk groups. In terms of gender, smoking history and second-hand tobacco smoking exposure history, two other groups named male and female never-smoker groups who were exposed to second-hand tobacco smoking were designated. The positive results were identified as at least one solid or part-solid nodule measuring ≥5 mm, or non-solid nodule ≥8 mm in diameter. LDCT scanning protocol, criteria of management according to the size and consistency of pulmonary nodules were compliant with the International Early Lung Cancer Active Program (I-ELCAP). TNM staging of all lung cancers were based on the clinical evidence and pathological findings. Results: In various risk status group of the participants, the percentage of positive results of baseline CT were 27.0% (86/319), 19. 3% (199/1 029) and 11.3% (377/3 342), respectively. A total of 26 participants (27 lesions) were diagnosed as lung cancer (11 in men, 15 in women). The detection rate of lung cancer was 0. 6% (26/4 690). Besides a SCLC (limited-disease, LD) 25 cases (76.0%) were stage I including 24 NSCLC and one cacinoid on baseline LDCT and the surgical resection rate was 88. 5% (23/26). The diameter of resected cancers was 6. 9-29. 5 mm (median, 16. 3 mm) For female never smokers aged 40 years or older who were exposed to second-hand smoking, the detection rate of lung cancer was higher than that of the high-risk and male never smokers who were exposed to second-hand smoking (1. 4% vs. 0. 9%, 0. 4%). Conclusions: The results indicate that LDCT can detect small lung cancers and most of the cancers are detected at an early stage. Emphasis should be placed on the non-smoking female individuals who are exposed to second-hand smoking in China.