Study Reveals Elevated Long-Term Lung Cancer Risk for Smokers After Negative Baseline LDCT Findings

A recent cohort study published in JAMA Network Open highlights the long-term lung cancer (LC) risk for smokers even after receiving negative baseline low-dose computed tomography (LDCT) results. The study, conducted within the Cancer Screening Program in Urban China, involved 30,565 participants aged 40 to 74 years and followed them until December 2023.

Participants underwent LDCT screening between October 1, 2013, and December 31, 2021, resulting in a cohort comprising 14,761 never smokers and 15,804 smokers. Of the latter, 10,278 had a history of 30 or more pack-years. The study monitored LC incidence and assessed the risk based on smoking status, pack-years, and time since quitting smoking.

Results revealed that smokers exhibited a significantly higher LC risk than never smokers, particularly those with a history of smoking 20 pack-years or more. Specifically, those with 30 or more pack-years had an adjusted hazard ratio (AHR) of 3.22 for developing LC. Notably, while the first two years post-screening showed no significant risk increase, the risk surged significantly from the third year onward.

The study also detailed a significant nonlinear dose-response relationship between smoking pack-years and LC risk, identifying 20 pack-years as a pivotal risk threshold. Interestingly, the increased risk was more pronounced in females at equivalent exposure levels and in older participants, particularly those aged 55 to 74 years.

Short-term cessation of smoking, defined as less than 15 years, did not significantly reduce LC risk among individuals with heavy smoking history, underscoring the enduring effects of long-term tobacco exposure.

These findings challenge current screening protocols, suggesting that smokers require more personalized, long-term monitoring beyond initial negative LDCT results. The study advocates for extending initial screening intervals and tailoring surveillance strategies based on individual smoking histories. Additionally, they caution that heavy smokers may require risk stratification incorporating age and sex to enhance screening efficacy and resource allocation.

The insights from this study emphasize the need for precision in lung cancer prevention strategies, suggesting that even negative baseline screenings do not equate to reduced long-term risk, particularly in populations with significant smoking histories. The research calls for extended screening intervals and continuous monitoring for smokers, aiming to refine current LDCT screening guidelines.