The Liverpool Lung Project (LLP) risk model demonstrated good discrimination and evidence of predicted benefits for stratifying patients into CT screening when it was applied to three independent studies, according to an analysis published Aug. 21 in Annals of Internal Medicine.
The National Lung Screening Trial has linked annual CT screening for three years with a 20 percent mortality reduction among a high-risk population. However, identifying persons at highest risk will produce a more favorable benefit-harm ratio. Various risk models may help steer such decisions.
The LLP model incorporates risk factors including smoking status and duration, history of pneumonia, history of non-lung cancer, asbestos exposure and family history.
Olaide Y. Raji, PhD, from the school of cancer studies at University of Liverpool Cancer Centre in England, and colleagues evaluated the model against three studies: the European Early Lung Cancer, the Harvard Case Control Studies and the LLP population-based prospective cohort (LLPC) study. The researchers extracted LLP risk factors from patient questionnaires. However, asbestos exposure information was unavailable for the LLPC study.
Raji and colleagues then used the LLP model to predict a person’s five-year risk for lung cancer. (Among the LLPC, the model was applied without asbestos exposure.)
When they reviewed risk distribution of the LLP model, control participants generally had lower individual absolute risks than case patients. “Most risks greater than 2.5 percent were predicted for patients with cancer, whereas about one half of disease-free patients had absolute risks less than 1 percent.”
In addition, in terms of discrimination, the model had higher ability than using smoking duration or family history of lung cancer.
Raji et al also assessed the model’s potential for clinical application and reported at a 5 percent threshold of absolute risk, the model achieved a higher proportion of true-positive classifications than a screen-all approach. “The LLP model had greater net benefit than all alternative strategies at thresholds of absolute risk ranging from 3 percent to 15 percent.”
The study demonstrated that the risk model has good ability to distinguish persons who will or will not develop lung cancer by using the predicted five-year absolute risk, according to Raji and colleagues. It also outperformed smoking duration and family history as a screening decision tool.
The researchers emphasized the need to develop and apply risk models to identify fewer persons for screening and identify a higher proportion of persons with lung cancer. The LLP model may be useful for selecting high-risk candidates for screening; however, further prospective evaluation is needed before clinical application in the primary care setting, Raji et al summed.