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 (RCTs). Objective: To assess real-world LDCT lung cancer screening (LCS) performance and factors predictive of adherence to LCS recommendations. Methods: We retrospectively identified all persons who underwent at least 2 LCS exams from 2014 to 2019. Patient demographics, smoking history and behavior changes, Lung-RADS category, PPV and NPV, and adherence to screening recommendations were recorded. Predictors of adherence were assessed via univariate comparisons and multivariate logistic regression. Results: 260 persons returned for follow-up LDCT (57.7% had two, 34.2% had three, 7.7% had four, and 0.4% had five). A total of 43/260 (16.5%) had positive scans, of which 28/260 (10.8%) were Lung-RADS category 3, 8/260 (3.1%) were 4A, 6/260 (2.3%) were 4B, and 2/260 (0.8%) were 4X. 4/260 were diagnosed with cancer (3 lung, 1 metastatic melanoma). 143/260 (55.0%) persons were current smokers at baseline and 121/260 (46.5%) were current smokers at the last round of LCS. LCS had sensitivity of 100.0%, specificity 84.8%, PPV 9.3%, and NPV 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: 53.9%; Lung-RADS 4A: 77.8%; Lung-RADS 4B: 83.3%; Lung-RADS 4X: 100.0%; p<0.001). Adherence was also higher in former vs. current smokers (50.0% vs 36.2%; p=0.002). Being a former smoker and a positive (≥3) Lung-RADS category were the only significant independent predictors of adherence. Conclusion: Our real-word LCS program demonstrated very high sensitivity and NPV, though moderate specificity and very low PPV. Adherence to LCS recommendations, increases in former, vs current smokers, and in those with positive LCS exams. Adherence was less than 50% in current smokers and persons with negative LCS exams. Clinical Impact: Our results offer a roadmap for targeted performance improvement by focusing on LCS subjects less likely to remain in the program, such as persons with negative LCS exams and persons who continue to smoke, potentially improving LCS cost-effectiveness and maximizing its societal benefits.