Non-calcified pulmonary nodules detected in low-dose computed tomography lung cancer screening programs can be potential precursors of malignancy

Non-specific pulmonary nodules detected in low-dose computed tomography (LDCT) lung cancer screening have been the subject of discussions for years. Lung nodules are detected in 20–50% of high-risk individuals undergoing lung cancer screening and may cause harm for patients due to the need for further CT surveillance or invasive procedures. A high proportion of detected non-specific pulmonary nodules is one of the drawbacks of lung cancer screening programs. Between 2009–2011 in Gdańsk, Poland, we conducted a single-arm observational lung cancer screening program (1) for individuals at high risk of developing lung cancer, aged 50–75, with at least 20 pack-years of smoking history. Among 8,649 people screened, nonspecific pulmonary nodules were found in 54% of participants and non-calcified nodules (NCNs) in 34%. Lung cancer was diagnosed in 1.24% [107] of all participants (1). Subsequently, to evaluate the lung cancer incidence in the study population in the 5 years follow-up we analyzed retrospectively the database of the Polish National Health Fund (pol. Narodowy Fundusz Zdrowia). During the 5 years of follow-up from the end of the screening program, lung cancer was detected in another 382 program participants, so in 4.42% of the whole cohort. The total number of program participants diagnosed with lung cancer was 488 (5.65%) in the period 2009–2016 and the mean annual lung cancer detection rate would have been 0.77% a year if the screening was continued (2). Recently, in Lung Cancer, Pinsky and Gierada published an interesting article entitled “Long-term cancer risk associated with lung nodules observed on low-dose screening CT scans” (3). The authors subjected to a long observation LDCT arm participants of the National Lung Screening Trial (NLST) (4). The risk of lung cancer in trial participants with both a detected lung nodule in the baseline scan and new incidental findings during the followup has been evaluated. Of the 26,309 subjects who underwent low-dose CT, 26.9% [7,090] had a NCN in the baseline examination. The analysis was also carried out from the perspective of specific lung lobes. Among 131,545 lung lobes, nodules were found in 7.2% [9,448] of them. More than 20% of these nodules had a diameter ≥8 mm. The main results were presented in rate-ratios (RRs), which were computed as the ratio of the lung cancer incidence rate in a NCN group divided by the lung incidence rate in a comparison group without NCN. Adjusted RRs for periods 0–4, 4–8 and 8–12 years of followEditorial Commentary