To study the prevalence of lung cancer in high risk non-smokers using low dose CT (LDCT).
METHOD AND MATERIALSThis was a prospective, nationwide and multicenter study sponsored by The Ministry of Health and Welfare. In a period from Feb. 2015 to Dec. 2015, 4,498 subjects (aged 33 to 75, mean age 61.6, 3.365 females) underwent LDCT for lung cancer screening. The major inclusion criteria were ages between 55-75, non-smoking or light ex-smoking history (< 10 pack-year and had quit > 15 years), and having one of the following risk factors: family history of lung cancer (n = 1,738, 38.9%), environmental tobacco smoking exposure (n = 3,382, 75.2%), TB/COPD history (n = 334, 7.4%), cooking index ≥ 110 (n = 1,769, 39.3%), and not using ventilator during cooking (n = 197, 4.4%). The LDCT was conducted mainly according to the guideline suggested by American College of Radiology. The mean effective radiation dose of LDCT was 1.064 mSv (SD = 0.316 mSv). A solid or part-solid (PS) nodule larger than 6 mm or pure ground glass nodule (GGN) larger than 5 mm in diameter was designated as positive finding on LDCT. Each Institute Review Board approved the project and an informed consent was obtained from each subject.
RESULTSOf 4,498 subjects, 4.395 (97.7%) conformed to the inclusion criteria. Among them, 19.9% of the subjects were considered positive on LDCT and 1.64% (n = 72) underwent invasive procedures. The final pathology showed 2 cases of atypical adenomatous hyperplasia, 14 cases of benign lesions, and 56 (1.27%) cases of lung cancer (adenocarcinoma in situ or AIS = 6, minimally invasive adenocarcinoma or MIA = 10, invasive adenocarcinoma or IVA = 40). Of 56 patients with lung cancer, 96% were stage I or less. The nodule of 6 AIS were GGN in 4, PS in 2, the nodule of the 10 MIA featured GGN in 6, PS in 4, and that of 40 IVA were GGN in 17, PS in 20, and solid in 3. The mean diameter ± SD of AIS, MIA and IVA were 11.50 ± 4.35, 11.77 ± 5.52, 13.4 ± 6.86, respectively.
CONCLUSIONOur study disclosed that the detection rate of lung cancer in high risk non-smokers by LDCT was comparable to that of the high risk smoking group in National Lung Screening Trial.
CLINICAL RELEVANCE/APPLICATIONRisk factors other than active smoking play a significant role in the etiologies of lung cancer in this area. LDCT might be used to screen lung cancer in high risk population without active smoking.