Analysis of lung cancer risk model (PLCO_M2012 and LLP_v2) performance in a community-based lung cancer screening...

Low-dose CT (LDCT) screening of high-risk smokers reduces lung cancer (LC) specific mortality. Determining screening eligibility using individualised risk may improve screening effectiveness and reduce harm. Here, we compare the performance of two risk prediction models (PLCO_M2012 and Liverpool Lung Project model (LLP_v2)) and National Lung Screening Trial (NLST) eligibility criteria in a community-based screening programme.

Ever-smokers aged 55-74, from deprived areas of Manchester, were invited to a Lung Health Check (LHC). Individuals at higher risk (PLCO_M2012 score ≥1.51%) were offered annual LDCT screening over two rounds. LLP_v2 score was calculated but not used for screening selection; ≥2.5% and ≥5% thresholds were used for analysis.

PLCO_M2012 ≥1.51% selected 56% (n=1429) of LHC attendees for screening. LLP_v2 ≥2.5% also selected 56% (n=1430) whereas NLST (47%, n=1188) and LLP_v2 ≥5% (33%, n=826) selected fewer. Over two screening rounds 62 individuals were diagnosed with LC; representing 87% (n=62/71) of 6-year incidence predicted by mean PLCO_M2012 score (5.0%). 26% (n=16/62) of individuals with LC were not eligible for screening using LLP_v2 ≥5%, 18% (n=11/62) with NLST criteria and 7% (n=5/62) with LLP_v2 ≥2.5%. NLST eligible Manchester attendees had 2.5 times the LC detection rate than NLST participants after two annual screens (≈4.3% (n=51/1188) vs 1.7% (n=438/26 309); p<0.0001). Adverse measures of health, including airflow obstruction, respiratory symptoms and cardiovascular disease, were positively correlated with LC risk. Coronary artery calcification was predictive of LC (_adjOR 2.50, 95% CI 1.11 to 5.64; p=0.028).

Prospective comparisons of risk prediction tools are required to optimise screening selection in different settings. The PLCO_M2012 model may underestimate risk in deprived UK populations; further research focused on model calibration is required.