Collateral and incidental findings in lung cancer screening with low-dose CT: preliminary single-centre experience from the RISP trial

Background: Lung cancer is the leading cause of cancer-related deaths globally. Lung cancer screening with low-dose CT not only enables reducing mortality in heavy smokers but also offers the chance to identify potential clinically significant collateral and incidental findings, such as coronary artery calcifications, emphysema, and interstitial lung abnormalities. Reporting these findings may allow for early detection of unknown actionable conditions, yet there is little data on prospectively handled collateral and incidental findings in lung cancer screening. Objective: The primary aim of the study was to analyse the preliminary data regarding potential clinically relevant collateral and incidental findings in a group of RISP trial volunteers enrolled at the San Luigi Gonzaga Hospital in Orbassano (Turin). Methods: Consecutive 400 volunteers who underwent baseline low-dose CT at San Luigi Gonzaga Hospital in Orbassano (Turin) as part of the RISP trial were initially considered for the study. Of them, we selected those categorised as Lung-RADS S based on the prospective radiological report, namely those who showed at least one possibly significant incidental or collateral finding on the baseline screening round. Data on downstream investigations and therapeutic interventions were gathered by directly contacting patients by phone. The inclusion criteria were the ones previewed by the screening programme. Results: A total of 108 (27%) of the 400 volunteers reported positivity for collateral and incidental findings. Overall, 122 findings were reported, with the most encountered ones being coronary artery calcifications (28, 23%), followed by interstitial lung abnormalities (17, 13.9%). A downstream clinical evaluation with a specialist involved 72.2% (78) of the Lung-RADS S volunteers; second-level diagnostic tests and a new therapy were prescribed in 39.8% (43) and 19.4% (21) of cases, respectively. Among the collateral findings, 27% (12) underwent active treatment, while 11.4% (5) warranted monitoring. Among incidental findings, 17% (9) required active treatment and 18.9% (10) monitoring. Out of the 122 findings, 18 (14.7%) were not evaluated despite the indication on the radiological report. Conclusions: Nearly one-third of the participants had potentially clinically relevant collateral or incidental findings reported on the first round of a national lung cancer screening programme. Identifying such findings can be beneficial, as it offers the opportunity to early diagnose actionable disorders in unaware high-risk smoking subjects. The present analysis highlights a good adherence of lung cancer screening volunteers to recommendations suggested in the report, yet the management of collateral and incidental findings suffers from heterogeneity when handled by territorial healthcare. Recommendations tailored to the healthcare system and considering the cost-benefit ratio would help optimise lung cancer screening volunteers' management and personalise intervention.