Lung cancer persists as the deadliest cancer worldwide, not only affecting those with a history of smoking but also individuals who have never smoked (LCINS). This growing subset now ranks as the seventh most common cancer globally and the fifth leading cause of cancer-related deaths. Identifying the unique risks and addressing the complexities of screening for LCINS are critical steps in reducing its burden and improving outcomes.
The Increasing Prevalence of Lung Cancer Among Non-Smokers
For decades, lung cancer has been closely linked to smoking. Yet, a significant rise in cases among non-smokers has challenged this perception. Dr. Aaron Mansfield from Mayo Clinic highlights, “People who smoke have the greatest risk of developing lung cancer, but it can occur in people who don’t smoke, as well.” This demonstrates how lung cancer risk extends beyond smoking. Source – Mayo Clinic
LCINS (Lung Cancer in Never-Smokers) is particularly prevalent among women, individuals with Asian ancestry, and those with a family history of the disease. Unlike smoking-related lung cancer, LCINS primarily presents as adenocarcinoma—a distinct pathology requiring tailored approaches to detection and management.
Environmental factors, including exposure to pollutants, second-hand smoke, and genetic predisposition, are thought to contribute to LCINS risk. We need to raise awareness and take preventive steps to tackle these risks that aren’t caused by behaviour, helping to protect more people.
Low-Dose CT Scans in Lung Cancer Screening
Low-dose computed tomography (LDCT) has proven effective in reducing lung cancer mortality in smokers with high exposure histories. It works by detecting early-stage cancers, often before symptoms appear, allowing for prompt and potentially life-saving interventions. However, the use of LDCT for screening individuals who have never smoked poses a more complex challenge.
A significant concern with LDCT in non-smokers is the issue of overdiagnosis—the detection of slow-growing or non-lethal lesions that are unlikely to progress into aggressive disease. Research has shown that many of these early detections lead to invasive follow-up procedures, including surgical interventions that carry risks such as infection, bleeding, or even mortality rates of up to 2%.
For instance, a South Korean study examining opportunistic LDCT screening in over 21,000 non-smokers found that 0.8% of participants were diagnosed with lung cancer, with most presenting subsolid nodules typical of adenocarcinoma spectrum diseases. While detection rates are encouraging, 93% of the cases represented early-stage or precancerous conditions, raising significant concerns about unnecessary treatment.
The Risks of Overdiagnosis
Overdiagnosis has profound implications for patients and healthcare systems. For non-smokers, lung cancer detected during screening often includes conditions like minor nodules or adenocarcinoma in situ—non-aggressive conditions that may not progress in a person’s lifetime. Unnecessary treatments for these can lead to severe physical, psychological, and financial burdens.
An example of the potential harm comes from a Taiwanese study that reported a sharp rise in early-stage lung cancer diagnoses after implementing widespread LDCT screening. The study showed no drop in advanced lung cancer cases or deaths, highlighting the problems and risks of overdiagnosing.
Moving Towards More Targeted Screening
Given the lower overall risk of lung cancer among non-smokers compared to smokers, blanket screening programmes lack cost-efficiency and may expose individuals to undue harm. Instead, the focus should shift towards targeted screening strategies.
Future approaches should rely on identifying high-risk subgroups—such as those with relevant genetic markers, family history, or prolonged exposure to environmental triggers—and employing precision diagnostics. This data-driven method ensures that screening and subsequent interventions are performed only where the benefit clearly outweighs the risk.
Targeted research is already underway. Observational studies in regions with higher LCINS prevalence, including Asia and among specific demographics in the US, seek to refine screening protocols. Efforts are also ongoing to improve the accuracy of diagnostic tools, reducing false positives and limiting unnecessary treatments.
Supporting Prevention as a Core Strategy
While advances in screening are essential, prevention remains the most effective way to combat lung cancer. Encouraging individuals to avoid avoidable risks, such as exposure to harmful substances, remains a fundamental pillar for reducing LCINS. Promoting universally healthy lifestyles, coupled with rigorous environmental regulation, can significantly diminish the disease’s prevalence over time.
Raising awareness about LCINS risk factors and detecting symptoms early can empower communities to make informed health decisions, strengthening public health’s role in cancer prevention.
Building a Safer Future
The rise in LCINS cases highlights a pressing need for deliberate, evidence-based strategies to address this silent health crisis. Overdiagnosis, while well-intentioned through opportunistic screening, must be carefully avoided to protect patients from physical and emotional strain. Focusing on smart screening and strong prevention can make a real difference by saving lives and helping people stay healthier, while making the most of the resources we have.
Together, public health systems, clinicians, and communities can work towards a future where lung cancer diagnoses are minimised, and those affected receive the most appropriate care possible.
Source: JAMA Network
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