Lung cancer screening: New evidence, updated guidance
Emerging evidence supports lower thresholds for age and smoking history when screening for lung cancer. Here’s how the USPSTF and others have updated their guidelines in response.
PRACTICE RECOMMENDATIONS
› Recommend annual lung cancer screening for all highrisk adults ages 50 to 80 years using low-dose computed tomography. A
› Do not pursue lung cancer screening in patients who quit smoking ≥ 15 years ago, have a health problem that limits their life expectancy, or are unwilling to undergo lung surgery. A
› Recommend varenicline as first-line pharmacotherapy for smokers who would like to quit. C
Strength of recommendation (SOR)
A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series
The NELSON trial, conducted between 2005 and 2015, studied more than 15,000 current or former smokers ages 50 to 74 years and compared LDCT screening at various intervals to no screening.13 After 10 years, lung cancer–related mortality was reduced by 24% (or 1 less death per 1000 person-years) in men who were screened vs their unscreened counterparts.13 In contrast to the NLST, in the NELSON trial, no significant difference in all-cause mortality was observed. Subgroup analysis of the relatively small population of women included in the NELSON trial suggested a 33% reduction in 10-year mortality; however, the difference was nonsignificant between the screened and unscreened groups.13
Each of these landmark studies had characteristics that could limit the results' generalizability to the US population. In the NELSON trial, more than 80% of the study participants were male. In both trials, there was significant underrepresentation of Black, Asian, Hispanic, and other non-White people.12,13 Furthermore, participants in these studies were of higher socioeconomic status than the general US screening-eligible population.
At this time, LDCT is the only lung cancer screening modality that has shown benefit for both disease-related and all-cause mortality, in the populations that were studied. Based on the NLST, the number needed to screen (NNS) with LDCT to prevent 1 lung cancer–related death is 308. The NNS to prevent 1 death from any cause is 219.6
Updated evidence has led to a consensus on screening criteria
Many national societies endorse annual screening with LDCT in high-risk individuals (TABLE 16-10). Risk assessment for the purpose of lung cancer screening includes a detailed review of smoking history and age. The risk of lung cancer increases with advancing age and with cumulative quantity and duration of smoking, but decreases with increasing time since quitting. Therefore, a detailed smoking history should include total number of pack-years, current smoking status, and, if applicable, when smoking cessation occurred.
In 2021, the US Preventive Services Task Force (USPSTF) updated their 2013 lung cancer screening recommendations, expanding the screening age range and lowering the smoking history threshold for triggering initiation of screening.6 The impetus for the update was emerging evidence from systematic reviews, RCTs, and the Cancer Intervention and Surveillance Modeling Network (CISNET) that could help to determine the optimal age for screening and identify high-risk groups. For example, the NELSON trial, combined with results from CISNET modeling data, showed an empirical benefit for screening those ages 50 to 55 years.6
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