Current lung cancer screening: a call for comprehensive reassessment

We read the study by Zhu et al. (1) investigating the association between long-term exposure to fine particulate matter (PM2.5) and lung cancer incidence in non-smokers. This study provides crucial insights, revealing a significant association between PM2.5 exposure and the risk of lung cancer in non-smokers. Higher incidence and mortality were observed in individuals with high genetic risk. Notably, approximately 34% of lung cancer incidence in non-smokers and 49% of lung cancer-related mortality could be prevented by reducing PM2.5 levels.

The role of carcinogens in tobacco smoke in initiating and advancing lung cancer has been well established for a long time. Consequently, substantial research has been conducted to explore the advantages of utilizing chest computed tomography (CT) for diagnosing lung cancer among smokers. For example, the NELSON trial examined the influence of volume CT lung cancer screening in high-risk smokers, and the study results showed the benefits of volume CT screening (2). Another example is the National Lung Screening Trial which assessed the efficacy of low-dose CT (LDCT) screening compared to chest radiography for detecting lung cancer in high-risk participants. Participants aged 55 to 74 with a minimum history of 30 pack-years of smoking were enrolled in this trial. Results indicated a 20% decrease in lung cancer mortality in the LDCT group compared to the chest radiography group (3). Numerous multivariate lung cancer prediction models have been developed for smokers, including PLCOm2012, LCRAT, LCDRAT, and others created in the United States and Europe. One study further refined a risk model for Asians, resulting in the “Shanghai Model”, which has been externally validated in other Asian cohorts (4).

Based on those studies, lung cancer screening with LDCT has been widely adopted for smokers in many countries. However, the current screening strategies based on smoking status do not appropriately address the increasing incidence of lung cancer among non-smokers. This indicates a need for a paradigm shift to include never-smokers who are at higher risk of lung cancer, beyond only focusing on traditional high-risk smoking people. Reflecting this view, recent studies are trying to include never-smokers in LDCT screening (5). However, as LDCT screening for smokers targets high-risk groups, LDCT screening for never-smokers should be performed in high-risk groups to minimize radiation exposure and enhance cost-effectiveness. To do this, efforts to reveal various non-smoking-related risk factors, including secondhand smoke, outdoor air pollutants, indoor cooking, family history, and chronic airway diseases [chronic obstructive pulmonary disease (COPD), bronchiectasis, etc.] are needed (1,6,7). From this perspective, Zhu et al. have made a great contribution in this field. The major advantage of their study is that they comprehensively considered second-hand smoke exposure and COPD. However, unfortunately, they did not consider pulmonary tuberculosis history, which is very prevalent worldwide, including in their country. The relationship between PM2.5 concentrations and tuberculosis development has already been studied (8,9); therefore, it would have been valuable for this study to include additional discussion of tuberculosis when addressing the link between particulate matter and lung cancer.

Moreover, this study lacks data on occupational history. Individuals with known or suspected exposure to lung carcinogens, or those engaged in jobs or tasks associated with increased lung cancer risk, are considered eligible for lung cancer screening. Key carcinogens include asbestos, silica, diesel exhaust, welding fumes, certain metals, and radiation. Although the burden of disease and mortality is substantial, occupational lung cancer remains largely overlooked in public health monitoring, clinical practice, and workers’ compensation programs. Research conducted across multiple populations and industries in Asia, Europe, and North America has found that fewer than 3% of estimated occupational lung cancer cases are officially recognized as work-related (10). Since recent studies have suggested that pulmonary tuberculosis history (6,11,12) and occupational carcinogen exposure (10) are associated with an increased risk of lung cancer even when considering COPD and smoking status, we would like to raise the question of whether pulmonary tuberculosis and occupational history modifies the effect of the association between PM2.5 exposure and lung cancer risk in their study.

The recent identification of non-smoking-related novel risk factors for lung cancer is encouraging. These results will unveil many aspects of lung cancer etiologies beyond the era of solely focusing on smoking status. Although the current lung cancer screening strategies only consider age, sex, and simple smoking history, the growing efforts to uncover non-smoking-related risk factors will pave the way for developing personalized lung cancer screening models. The new tools should include factors such as secondhand smoke exposure, exposure to outdoor/indoor pollutants, family history, occupational history, pulmonary comorbidities (e.g., pulmonary tuberculosis history, COPD, and bronchiectasis). We also suggest that, given the differences in lung cancer characteristics between Western and Asian populations, developing predictive models tailored to the unique characteristics of each group is important.

Acknowledgments

None.

Footnote

Provenance and Peer Review: This article was a standard submission to the journal. The article has undergone external peer review.

Peer Review File: Available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-384/prf

Funding: This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (RS-2025-00557268) and research fund of Hanyang University (HY-202500000001668).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jtd.amegroups.com/article/view/10.21037/jtd-2025-384/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

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