Abstract:

Objective: To analyze the results of low-dose CT(LDCT) screening for lung cancer in asymptomatic patients. Methods: From April 2015 to April 2018, 22 351 asymptomatic patients(16—95 years old) underwent lung LDCT examination. According to the size and type of nodules, they were divided into positive nodules, semi-positive nodules and negative nodules. The results of LDCT lung nodule detection and lung cancer screening in different age groups and gender groups were analyzed. Detection of different types of nodule in positive and semi-positive nodules was analyzed too. The changes of nodule during follow-up were recorded. Results: The total detection rate of pulmonary nodule was 31%. The detection rates in male and female were 34.1% and 28.8%, respectively; the difference was significant ( χ²=70.47, P<0.001). The detection rate of nodule was different in different age groups, and the difference was statistically significant ( χ²=1 032.96, P<0.001). The older the age group, the higher the detection rate of nodule. The detection rate of nodule in 81—95 age group was the highest (50.0%). The detection rate of positive nodules was different in different genders, the difference was statistically significant ( χ²=184.36, P<0.001). The detection rate of positive nodules in male population (10.1%) was higher than that in female group (8.6%). The detection rate of positive nodules was different in different age groups, and the difference was statistically significant ( χ²= 434.89, P<0.001). The overall detection rate of lung cancer was 0.4%. Forty-eight cases of lung cancer were detected by baseline screening, and 47 cases of lung cancer were detected by follow-up within 36 months. There was a significant difference in detection rate of lung cancer between different genders ( χ²=7.52, P=0.006). The detection rate of lung cancer in male and female was about 0.6% and 0.3%, respectively. The detection rate of lung cancer in patients over 50 years old was significantly higher than those under 50 years old, and the detection rate was about 0.7% and 0.1%, respectively. The difference was statistically significant ( χ²=42.20, P=0.006). P<0.001). The detection rates of lung cancer in positive and semi-positive nodule groups were 4.5% and 0.1%, respectively. The difference was statistically significant ( χ²=207.78, P<0.001). The proportion of positive and semi-positive nodule in nodules of different density types was different ( χ²=267.06, P<0.001). The detection rate of malignant nodule in different density types was different, the difference was statistically significant ( χ²=131.77, P<0.001). The detection rate of malignant nodule in part-solid nodules was high, up to 4.3%. During the follow-up period, 4 557 patients with semi-positive nodules underwent annual review or biennial review, and only 2 patients were pathologically confirmed as early lung cancer. Malignant nodules accounted for 0.7% of the detected nodules.Conclusions: LDCT lung cancer screening is very important for middle-aged and elderly people, especially those over 50 years old. For semi-positive nodules, annual review is feasible. For the screened pulmonary nodules, the overall proportion of malignant nodules (0.7%) is low. A reasonable follow-up management plan should be formulated according to the size, type and morphological characteristics of nodules.

Key words: Pulmonary nodules, Screening, Low-dose CT