A new study established a model to predict the risk of lung cancer entitled “Evaluation of the Lung Cancer Risks at Which to Screen Ever- and Never-Smokers: Screening Rules Applied to the PLCO and NLST Cohorts”. It was published in PLOS Medicine by Martin C. Tammemägi from the Department of Health Sciences at Brock University in Canada, and identifies a threshold value for the probability of developing lung cancer that will enable the selection of subjects for an annual screening of lung cancer.

Lung cancer accounts for 17% of all cancer deaths. The disease has a very poor prognosis due to the fact that it is typically discovered in its late stages, and its incidence and death rates are around 5 million cases per year. Lung cancer is more common in men and has an occurrence of approximately 46.8 cases per 100,000 subjects in Europe and the United States. In cancer, cells acquire genetic defects that induce uncontrollable growth, ultimately leading to their spread through the body forming metastases. In lung cancer, the most frequent stimuli for these genetic mutations is exposure to cigarette smoke. Notably, lung cancer in non-smokers is an important public health concern, since it accounts for 10%–15% of all lung cancer cases, and is the seventh cause of death by cancer. Unfortunately, most lung cancers are normally detected when they are in an advanced stage, and fewer than 17% of patients will survive five years. However, it is still not clear which criteria should be used to choose subjects for lung cancer screening. Nevertheless, some experts suggest that risk prediction models for diagnosis, i.e. statistical models that estimate risk based on various personal characteristics, should be used to select individuals for screening.

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In this study, the researchers evaluated the lung cancer risk prediction model (PLCO_m2012), using the frequency of lung cancer in smokers recruited for the US Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO). The research team used the screening results from the US National Lung Screening Trial (NLST) and PLCO to identify a PLCO_m2012 risk threshold to select individuals for screening. In addition, they compared the efficiency of the PLCO_m2012 model and the US Preventive Services Task Force (USPSTF) criteria, which is one computed tomography CT screening per year for individuals who are 55–80 years old, smokers of more than 30 packs a year (one pack-year means a pack of cigarettes per day during a year), and for former smokers that stopped smoking less than 15 years ago, to select the individuals that should be screened.

In conclusion, the researchers found that using the PLCO_m2012 risk ≥0.0151 criteria for the selection of subjects for annual low-dose computed tomography (LDCT) screening may improve screening efficiency than using the selection by US Preventive Services high-risk older smokers (≥65–80 y)Task Force (USPSTF) criteria. In addition, non-smokers should not be screened but high-risk older smokers (≥65–80 y) should be selected for lung cancer screening.

“This should make lung cancer screening more attractive for policy-makers and more affordable for health systems.” concluded the authors in a press release.