Interstitial Lung Abnormalities and Lung Cancer Risk in the National Lung Screening Trial

BACKGROUND

Some interstitial lung diseases are associated with lung cancer. However, it is unclear whether asymptomatic interstitial lung abnormalities convey an independent risk.

OBJECTIVES

The goal of this study was to assess whether interstitial lung abnormalities are associated with an increased risk of lung cancer.

METHODS

Data from all participants in the National Lung Cancer Trial were analyzed, except for subjects with preexisting interstitial lung disease or prevalent lung cancers. The primary analysis included those who underwent low-dose CT imaging; those undergoing chest radiography were included in a confirmatory analysis. Participants with evidence of reticular/reticulonodular opacities, honeycombing, fibrosis, or scarring were classified as having interstitial lung abnormalities. Lung cancer incidence and mortality in participants with and without interstitial lung abnormalities were compared by using Poisson and Cox regression, respectively.

RESULTS

Of the 25,041 participants undergoing low-dose CT imaging included in the primary analysis, 20.2% had interstitial lung abnormalities. Participants with interstitial lung abnormalities had a higher incidence of lung cancer (incidence rate ratio, 1.61; 95% CI, 1.30-1.99). Interstitial lung abnormalities were associated with higher lung cancer incidence on adjusted analyses (incidence rate ratio, 1.33; 95% CI, 1.07-1.65). Lung cancer-specific mortality was also greater in participants with interstitial lung abnormalities. Similar findings were obtained in the analysis of participants undergoing chest radiography.

CONCLUSIONS

Asymptomatic interstitial lung abnormalities are an independent risk factor for lung cancer that can be incorporated into risk score models.

Progression of probable UIP and UIP on HRCT

PURPOSE

To determine patterns of progression of probable Usual Interstitial Pneumonitis (UIP).

METHODS

This HIPPA compliant, IRB-approved study draws patients from our Fibrosis Registry. All patients with a consensus diagnosis of Idiopathic Pulmonary Fibrosis (IPF) were included. Most recent CT scans and all earlier CT scans were reviewed to determine the fibrosis grade in each lobe based on probable UIP (pUIP) findings of ground glass opacities, traction bronchiolectasis and reticulations or UIP findings of subpleural basilar predominant fibrosis with honeycombing (HC) and absence of features that would suggest an alternative diagnosis.

RESULTS

103 patients with a working diagnosis of IPF are the focus of this report. Among the 68 with pUIP on the initial CT, 32 (47%) progressed; median time to progression was 51 months. The risk of HC progression, adjusted for gender, of patients with emphysema was 2.53 times higher than patients without emphysema (HR = 2.53, 95% CI: 1.06-6.02). Among the 35 with HC on the initial CT scan, 20 (57%) progressed to more advanced HC; median time to progression was 31 months. Increased pulmonary artery size was significantly associated with an elevated risk for more advanced HC progression (HR = 1.16, 95% CI: 1.04-1.31).

CONCLUSION

Ground glass opacities, traction bronchiolectasis and reticulations, a "Probable UIP Pattern" by ATS criteria progressed to UIP in 47% of patients on follow-up imaging.

Survival with Parenchymal and Pleural Invasion of Non-Small Cell Lung Cancers Less than 30 mm

OBJECTIVE

To determine long-term survival of visceral pleural invasion (VPI) and parenchymal invasion (PAI) (angiolymphatic and/or vascular) on survival of NSCLCs less than 30 mm in maximum diameter.

METHODS

Kaplan-Meier survivals for NSCLCs, with and without VPI and/or PAI, were determined for a prospective cohort of screening participants stratified by pathologic tumor size (≤10 mm, 11-20 mm, and 21-30 mm) and nodule consistency. Log-rank test statistics were calculated.

RESULTS

The frequency of PAI versus VPI was significantly lower in patients with subsolid nodules than in those with solid nodules (4.9% versus 27.7% [p < 0.0001]), and correspondingly, Kaplan-Meier lung cancer survival was significantly higher among patients with subsolid nodules (99.1% versus 91.3% [p = 0.0009]). Multivariable Cox regression found that only tumor diameter (adjusted hazard ratio [HR] =1.07, 95% confidence interval [CI]: 1.01-1.14, p = 0.02) and PAI (adjusted HR = 3.15, 95% CI: 1.25-7.90, p = 0.01) remained significant, whereas VPI was not significant (p = 0.15). When clinical and computed tomography findings were included with the pathologic findings, Cox regression showed that the risk of dying of lung cancer increased 10-fold (HR = 10.06, 95% CI: 1.35-75.30) for NSCLCs in patients with solid nodules and more than twofold (by a factor of 2.27) in patients with moderate to severe emphysema (HR = 2.27, 95% CI: 1.01-5.11), as well as with increasing tumor diameter (HR = 1.06, 95% CI: 1.01-1.13), whereas PAI was no longer significant (p = 0.19).

CONCLUSIONS

Nodule consistency on computed tomography was a more significant prognostic indicator than either PAI or VPI. We propose that patients with NSCLC with VPI and a maximum tumor diameter of 30 mm or less not be upstaged to T2 without further large, multicenter studies of NSCLCs, stratified by the new T status and that classification be considered separately for patients with subsolid or solid nodules.