Incorporating Baseline Lung Function in Lung Cancer Screening: Does a "Lung Health Check" Help Predict Outcomes?

Should we be screening for COPD? - looking through the lens of lung cancer screening

INTRODUCTION

In May 2022, the US Preventive Services Task Force published their recommendation against screening for chronic obstructive pulmonary disease (COPD) in asymptomatic adults. However, we argue the routine use of spirometry in both asymptomatic and symptomatic high-risk smokers has utility.

AREAS COVERED

We provide published and unpublished observations from a secondary analyses of the American College of Radiology Imaging Network (ACRIN), arm of the National Lung Screening Trial, including 18,463 high-risk current or former smokers who underwent pre-bronchodilator spirometry at baseline. According to history alone, 20% reported a prior diagnosis of 'COPD,' although only 11% (about one half), actually had airflow limitation (Diagnosed COPD) and 9% had Global Initiative for Obstructive Pulmonary Disease GOLD 0 Pre-COPD. Of the remaining 80% of 'asymptomatic' screening participants, 23% had airflow limitation (Screen-detected COPD) and 13% had preserved ratio impaired spirometry (PRISm). This means 45% of this high-risk cohort were reclassified by spirometry, and together with comorbid disease, identified subgroups where lung cancer screening efficacy could be optimized by between 2-6 fold.

EXPERT OPINION

Our preliminary findings suggest lung cancer screening outcomes vary according to 'new' COPD-related spirometric-defined subgroups and that screening spirometry, together with comorbid disease, identifies those for whom lung cancer screening is mostly beneficial or potentially harmful.

Airflow limitation and mortality during cancer screening in the National Lung Screening Trial: why quantifying airflow limitation matters

Importance

Current eligibility criteria for lung cancer (LC) screening are derived from randomised controlled trials and primarily based on age and smoking history. However, the individual benefits of screening are highly variable and potentially attenuated by co-morbidities such as advanced airflow limitation (AL).

Objective

To examine the relationship between the presence and severity of AL and screening outcomes.

Methods

This was a secondary analysis of 18 463 high-risk smokers, a substudy from the National Lung Screening Trial, who underwent pre-bronchodilator spirometry at baseline and median follow-up of 6.1 years. We used descriptive statistics and a competing risk proportional hazards model to examine differences in screening outcomes by chronic obstructive pulmonary disease severity group.

Results

The risk of developing LC increased with worsening AL (effect size=0.34, p<0.0001), as did the risk of dying of LC (effect size=0.35, p<0.0001). While those with severe AL (Global Initiative for Obstructive Lung Disease, GOLD grade 3–4) had the highest risk of LC and the highest LC mortality, they also had fewer adenocarcinomas (effect size=−0.20, p=0.008) and a lower surgery rate (effect size=−0.16, p=0.014) despite comparable staging, and greater non-LC mortality relative to LC mortality (effect size=0.30, p<0.0001). In participants with no AL, screening with CT was associated with a significant reduction in LC deaths relative to chest X-ray (30.3%, 95% CI 4.5% to 49.2%, p<0.05). The clinically relevant but attenuated reduction in those with AL (18.5%, 95% CI −8.4% to 38.7%, p>0.05) could be attributed to GOLD 3–4, where no appreciable mortality reduction was observed.

Conclusion

Despite a greater risk of LC, severe AL was not associated with any apparent reduction in LC mortality following screening.

Airflow Limitation Increases Lung Cancer Risk in Smokers: The Lifelines Cohort Study

BACKGROUND

The relationship between smoking, airflow limitation, and lung cancer occurrence is unclear. This study aims to evaluate the relationship between airflow limitation and lung cancer, and the effect modification by smoking status.

METHODS

We included participants with spirometry data from Lifelines, a population-based cohort study from the Northern Netherlands. Airflow limitation was defined as FEV1/FVC ratio < 0.7. The presence of pathology-confirmed primary lung cancer during a median follow-up of 9.5 years was collected. The Cox regression model was used and hazard ratios (HR) with 95% confidence interval (95% CI) were reported. Adjusted confounders included age, sex, educational level, smoking, passive smoking, asthma status and asbestos exposure. The effect modification by smoking status was investigated by estimating the relative excess risk due to interaction (RERI) and the ratio of HRs with 95% CI.

RESULTS

Out of 98,630 participants, 14,200 (14.4%) had airflow limitation. In participants with and without airflow limitation, lung cancer incidence was 0.8% and 0.2%, respectively. The adjusted HR between airflow limitation and lung cancer risk was 1.7 (1.4-2.3). The association between airflow limitation and lung cancer differed by smoking status [former smokers: 2.1 (1.4-3.2), current smokers: 2.2 (1.5-3.2)] and never smokers [0.9 (0.4-2.1)]. The RERI and ratio of HRs was 2.1 (0.7-3.4) and 2.5 (1.0-6.5) for former smokers, and 4.6 (95% CI, 1.8-7.4) and 2.5 (95% CI, 1.0-6.3) for current smokers, respectively.

CONCLUSIONS

Airflow limitation increases lung cancer risk and this association is modified by smoking status.

IMPACT

Ever smokers with airflow limitation are an important target group for the prevention of lung cancer.