Lung Cancer Diagnosis Rates in Early Detection Programs in the Mississippi Delta

Importance: Estimates of the impact of lung cancer screening (LCS) largely rely on the 3.97% lung cancer diagnosis rate (LCDR) from the National Lung Screening Trial. Objective: To estimate the LCDR in clinical LCS and incidental pulmonary nodule (IPN) programs. Design, Setting, and Participants: This prospective cohort study of a large regional community health care system in the Mississippi Delta included patients who had at least 1 low-dose computed tomography (CT) scan for lung cancer or any CT scan finding an IPN diameter of 30 mm or less and no prior history of lung cancer between January 1, 2015, and June 30, 2024. Exposure: Patient surveillance in LCS or IPN programs. Main Outcomes and Measures: The primary outcome was aggregate LCDRs. Secondary outcomes were relative LCDRs stratified by baseline Lung CT Screening Reporting and Data System (Lung-RADS) score (LCS cohort) or nodule size (IPN cohort). Adjusted hazard ratios (AHRs) were estimated using a Cox proportional hazards model adjusted for age, sex, race, insurance, rurality, comorbidities, personal history of non-lung cancer, and family history of lung cancer. Results: Among 40 612 patients, 15 754 were enrolled in the LCS cohort (median [IQR] age, 65 [59-69] years; 7990 male [50.7%]) and 24 858 were enrolled in the IPN cohort (median [IQR] age, 64 [52-74] years; 13 919 female [56.0%]). Among patients in the LCS cohort, 13 517 (85.8%), 994 (6.3%), 559 (3.5%), 284 (1.8%), and 179 (1.1%) had Lung-RADS scores of 1 or 2, 3, 4A, 4B, and 4X, respectively. Among patients in the IPN cohort, 9204 (37.0%) had a baseline nodule diameter of less than 6 mm, 12 872 (51.8%) had a nodule of 6 to 15 mm, 1570 (6.3%) had a nodule of greater than 15 to 20 mm, and 1212 (4.9%) had a nodule of greater than 20 to 30 mm. The cumulative LCDR at 36 months was 3.8% (95% CI, 3.4%-4.1%) and 4.3% (95% CI, 4.1%-4.6%), with a median follow-up of 546 days (IQR, 237-996 days) and 647 days (IQR, 248-1279 days), in the LCS and IPN cohorts, respectively. With Lung-RADS 1 to 2 as the reference, AHRs were 3.38 (95% CI, 2.48-4.62), 7.41 (95% CI, 5.49-49.10), 25.46 (95% CI, 19.36-33.47), and 107.22 (95% CI, 82.76-138.19) for Lung-RADS 3, 4A, 4B, and 4X, respectively, and 0.59 (95% CI, 0.44-0.79), 2.66 (95% CI, 2.23-3.18), 9.93 (95% CI, 8.06-12.22), and 15.65 (95% CI, 12.67-19.32) for nodules less than 6 mm, 6 to 15 mm, greater than 15 to 20 mm, and greater than 20 to 30 mm in the IPN cohort. Five-year overall survival was 58% (95% CI, 52%-65%) and 46% (95% CI, 43%-50%) in the LCS vs IPN cohorts. Conclusions and Relevance: In this cohort study of LCS and IPN program patients, approximately 4% were diagnosed with lung cancer over less than half the duration of the NLST cohort, suggesting a greater population-level LCDR through these screening programs than estimated by clinical trial data.