Purpose Lung cancer risk models optimise screening by identifying subjects at highest risk, but none of them consider emphysema, a risk factor identifiable on baseline screen. Subjects with a negative baseline low-dose CT (LDCT) screen are at lower risk for subsequent diagnosis and may benefit from risk stratification prior to additional screening, thus we investigated the role of radiographic emphysema as an additional predictor of lung cancer diagnosis in participants with negative baseline LDCT screens of the National Lung Screening Trial.
Methods Our cohorts consist of participants with a negative baseline (T0) LDCT screen (n=16 624) and participants who subsequently had a negative 1-year follow-up (T1) screen (n=14 530). Lung cancer risk scores were calculated using the Bach, PLCOm2012 and Liverpool Lung Project models. Risk of incident lung cancer diagnosis at the end of the study and number screened per incident lung cancer were compared between participants with and without radiographic emphysema.
Results Radiographic emphysema was independently associated with nearly double the hazard of lung cancer diagnosis at both the second (T1) and third (T2) annual LDCT in all three risk models (HR range 1.9–2.0, p<0.001 for all comparisons). The number screened per incident lung cancer was considerably lower in participants with radiographic emphysema (62 vs 28 at T1 and 91 vs 40 at T2).
Conclusion Radiographic emphysema is an independent predictor of lung cancer diagnosis and may help guide decisions surrounding further screening for eligible patients.
- lung cancer
- risk assessment
- national lung screening trial
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Contributors PY takes responsibility for the article as a whole; PY, KMS, JPW, JPde-T, and JJZ conceived the study; JPde-T, JJZ and KMS obtained research funding; PY, KMS and JPW supervised the conduct of the study; PY, GM and MK analysed the data; PY, JPW, CYK, DW, S-AWB and CS interpreted analysis findings; PY drafted the manuscript, and all authors contributed substantially to its revision.
Funding Supported by National Cancer Institute (K07 CA180782 to KMS, K07 CA187071 to MK) and grant PI16/01149 Instituto de Salud Carlos II, Government of Spain. KMS and MK were supported in part by a career award from the National Cancer Institute. This work was supported in part by grant PI16/01149 from the Instituto de Salud Carlos II, Government of Spain. CS was supported by resources from the VA Portland Health Care System, Portland, Oregon, USA.
Disclaimer The funding source had no role in the design, conduct or reporting of this study or in the decision to submit the manuscript for publication. The views expressed in this article are those of the authors and do not necessarily represent the views of the Department of Veterans Affairs or the US Government.
Competing interests None declared.
Patient consent Not required.
Ethics approval The study was exempt by the Institutional Review Board of the Icahn School of Medicine at Mount Sinai.
Provenance and peer review Not commissioned; externally peer reviewed.
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