Lung cancer screening with low-dose CT: a study on risk factors and establishing the high-risk model for lung cancer

Objective To establish standards of high-risk populations for low-dose CT (LDCT) lung cancer screening projects by analyzing lung cancer risk factors. Methods LDCT was performed in 6 990 subjects undergoing physical examinations in Changzheng Hospital from September 2013 to September 2016, including 4 567 males and 2 423 females. Mineralization nodes, solid nodules, pure ground glass nodules and partial solid nodules were defined as positive results. All cases of lung cancer were confirmed by pathological examination. The morbidity and risk factors of lung cancer were analyzed using t-test, chi-square test and logistic regression analysis. And there were 13 risk factors involved, including age, sex, body mass index (BMI), smoking, the family history of lung cancer and other malignant tumors, the history of chronic bronchitis or chronic obstructive pulmonary disease, the history of pulmonary fibrosis, the history of tuberculosis, the history of other malignant tumors, the history of cardiovascular disease, the history of second hand smoke exposure, the history of exposure to radon and the history of exposure to asbestos. The cut point of risk factors was analyzed according to the receiver operating characteristic (ROC) curve. Results Sixty-nine cases of lung cancer and 85 malignant nodules were detected in this screening. There were 34 males and 35 females among the lung cancer patients and their age ranged from 24 to 88 years with an average age of (60±16) years. In all the factors involved in this study, sex (χ2=7.937), age (t=19.509, χ2=29.991) and cardiovascular disease (χ2=5.333) were proved to be the risk factors of lung cancer by single factor analysis. Logistic regression analysis showed that sex (OR=0.478, 95%CI: 0.297-0.769, P=0.002) and age (OR=1.024, 95%CI: 1.024-1.060, P=0.001) were independent risk factors of lung cancer. ROC analysis showed an area under the curve (AUC) of 0.62 for age, 0.587 for age of males and 0.659 for age of females. According to ROC curves, people over 56.5 years old (sensitivity 55.1%, specificity 75.0%, accuracy 74.8%), males over 56.5 years old (sensitivity 52.9%, specificity 73.4%, accuracy 73.3%) and females over 57.5 years old (sensitivity 57.1%, specificity 80.5%, accuracy 80.1%) were high-risk groups. Conclusions In this study, sex and age were proved to be the risk factors of lung cancer. Males over 56.5 years old and females over 57.5 years old are more likely to suffer from lung cancer. However, this study is a single center study, so that other risk factors of lung cancer are not ruled out completely. Key words: Lung neoplasms; Tomography, X-ray computed; Risk factors; Screening