The Study Of Low-Dose CT Screening For Early Lung Cancer

Objective To explore the effect of LDCT screening for early lung cancer,and to analyze the detection of pulmonary nodules, as well as the other lesions identified simultaneously. Materials and methods Between May 2014 and February 2016,786 participants were enrolled in this study. According to the NCCN(2014) guidelines, subjects were divided into high-risk individuals, moderate-risk individuals and low-risk individuals. And we divided into secondhand smoke exposure and without secondhand smoke exposure to analyze the screening results for non-smokers. The positive outcome for pulmonary nodules was identified to detect at least one more than 4mm in diameter of pulmonary non-calcified nodules. All LDCT images were inputed into PACS workstation. Radiologists read LDCT images and observe the nodules in lung and bronchial and recorded the average diameter, position, density and nature of the nodules. According to the NCCN(2014) guidelines, we conducted regular follow-up for subjects.For patients diagnosed with lung cancer, we recorded the method of diagnosis, pathological type, stage(based on AJCC in 2009), the time of baseline screening to surgery. Each group of the LDCT lung cancer screening results were analyzed in statistical method. Results At baseline screening, 786 subjects were recruited(549 men and 237 women). Median age was 56 years(range: 48 to 80 years). Of these subjects, 332(41.0%)were in high-risk individuals, 299(38.0%)in moderate-risk individuals and 165(21.0%)in low-risk individuals. There were 533 smokers(445 men,88 women) and 253 non-smokers(104 men, 149 women),including 175 secondhand smoke exposure and 88 without secondhand smoke exposure. The male smokers accounted for 81.0%(445/549)and the female non-smokers accounted for 62.9%(149/237). The difference of population between smokers and non-smokers gender was statistically significant(P<0.0001). Both male and femal of non-smokers had high secondhand smoke exposure rate(73.1% vs 66.4%),whereas difference between different gender was not statistically significant(P>0.05). Of these subjects, 97 cases(12.3%)had occupational exposure, 149 cases(19.0%)had family history and 68 cases(8.7%) had pulmonary disease. At baseline screening, the results of 160 subjects(20.4%) were positive, including 73(22.7%) in high-risk individuals, 58(19.4%) in moderate-risk individuals and 29(17.6%) in low-risk individuals. But the difference among groups was not statistically significant(P>0.05). The positive result rate of smokers was higher than non-smokers(22.5% vs 15.8%,P=0.029). There was no significant difference in the nodule detection rate between the secondhand smoke exposure group and the no secondhand smoke exposure group(P>0.05). 199 positive nodules were identified at baseline screening, and solid nodules, part-solid nodules and non-solid nodules were accounted for 179(90.0%),12(6.0%)and 8(4.0%)respectively, in which most nodules with diameter less than 6mm(55.8%), and the malignant rate of part-solid nodules was the highst(25%). Seven cases were confirmed as lung cancer by pathology. The detection rate of lung cancer was 0.89%(7/786), and there was no significant difference between male and female(0.5% vs 1.7%, P=0.207). Detection of lung cancer in individuals of various risk status did not show statistically significance(P>0.05). The lung cancer incidence rate of female in non-smokers was relatively high(2.0%). There was no significant difference in the detection rate of lung cancer between the secondhand smoke exposure group and the no secondhand smoke exposure group(P>0.05). There were 7 lesions in all cases. The mean diameter of cancers was 20.9mm(range 9.6~40.3mm). 6 cases with irregular shape(85.7%), and most lesions(71.4%) located in the right lung. The 7 screen-detected lung cancers were all non-small cell lung cancer, including 6 cases of adenocarcinoma, 1 cases of squamous cell carcinoma, of which 2 cases were confirmed with EGFR gene mutation. Detection rate of lung cancers was high, and stage IA was found in 6 cases(85.7 %). Emphysema was screened in 52 cases(6.6%), and the prevalence of emphysema for smokers was higher than non-somkers(9.0% vs 1.6%, P < 0.0001).Positive coronary arterial calcification were observed in 85 subjects(10.8%,85/786). Men with coronary arterial calcification proportion was higher than women(13.7% vs 4.2%, P = 0.022). coronary arterial calcification was more likely to occur in smokers than in non-smokers(12.6% vs 7.1%, P=0.021), and 4(4.7%) patients were confirmed to have cardiovascular disease during follow-up. Finally, the median effective dose of 786 subjects was 1.04mSV(rang 0.88~1.23mSv). Conclusion The results indicate that LDCT can detect early lung cancer with a high proportion 85.7% of stag-IA tumors. The effect of LDCT screening for lung cancer is significant. Early lung adenocarcinoma was the most common pathological type in identified lung cancer, accounting for 85.7%. The detection rate of female lung cancer in non-smokers was high, reaching 2%, and the screening of lung cancer for such individuals should be strengthened. The radiation dose was reduced markedly by LDCT. In parallel screening for lung cancer, we should pay attention to the detection of coronary arterial calcification and emphysema.