Real-World Lung Cancer CT Screening Performance, Smoking Behavior, and Adherence to Recommendations: Lung-RADS Category and Smoking Status Predict Adherence

Abstract

BACKGROUND. Low-dose CT (LDCT) lung cancer screening (LCS) has been shown to decrease mortality in persons with a significant smoking history. However, adherence in real-world LCS programs is significantly lower than in randomized controlled trials. OBJECTIVE. The purpose of this article is to assess real-world LDCT LCS performance and factors predictive of adherence to LCS recommendations. METHODS. We retrospectively identified all persons who underwent at least two LCS examinations from 2014 to 2019. Patient demographics, smoking history and behavior changes, Lung-RADS category, PPV, NPV, and adherence to screening recommendations were recorded. Predictors of adherence were assessed via univariate comparisons and multivariate logistic regression. RESULTS. A total of 260 persons returned for follow-up LDCT (57.7% had two, 34.2% had three, 7.7% had four, and 0.4% had five LDCT examinations). A total of 43 of 260 (16.5%) had positive (Lung-RADS category 3 or above) scans, of which 27 of 260 persons (10.3%) were graded as Lung-RADS category 3, eight of 260 (3.1%) were category 4A, six of 260 (2.3%) were category 4B, and two of 260 (0.8%) were category 4X. Cancer was diagnosed in four of the 260 (three with lung cancer and one with metastatic melanoma). A total of 143 of 260 (55.0%) persons were current smokers at baseline and 121 of 260 (46.5%) were current smokers at the last round of LCS. LCS had sensitivity of 100.0%, specificity of 84.8%, PPV of 9.3%, and NPV of 100%. Overall adherence was 43.0% but increased progressively with higher Lung-RADS category (Lung-RADS 1: 33.2%; Lung-RADS 2: 46.3%; Lung-RADS 3: 53.8%; Lung-RADS 4A: 77.8%; Lung-RADS 4B: 83.3%; Lung-RADS 4X: 100%; p < .001). was also higher in former versus current smokers (50.0% vs 36.2%; p < .001). Being a former smoker and having a nodule that is Lung-RADS category 3 or greater were the only significant independent predictors of adherence. CONCLUSION. Our real-world LCS program showed very high sensitivity and NPV, but moderate specificity and very low PPV. Adherence to LCS recommendations increased with former versus current smokers and in those with positive (Lung-RADS categories 3, 4A, 4B, or 4X) LCS examinations. Adherence was less than 50.0% in current smokers and persons with negative (Lung-RADS categories 1 or 2) LCS examinations. CLINICAL IMPACT. Our results offer a road map for targeted performance improvement by focusing on LCS subjects less likely to remain in the program, such as persons with negative LCS examinations and persons who continue to smoke, potentially improving LCS cost effectiveness and maximizing its societal benefits.

Keywords: CT; lung cancer; mass screening; patient adherence; smoking.