Analysis of recurrence in lung adenocarcinoma with spread through air spaces

Objectives: Spread through air spaces is defined as tumor cells in air spaces away from the edge of tumor in lung carcinoma. It is associated with higher locoregional recurrence and lower survival in lung adenocarcinoma. The features of spread through air spaces portending worse outcomes are still under investigation. We reviewed our lung cancer experience to define potential factors related to spread through air spaces that influence recurrence and survival.

Methods: Between January 2010 and December 2017, we identified 968 patients who underwent resection for T1-3N0M0 lung adenocarcinoma. Of these, histologic examination was possible in 787 patients. We examined the presence of spread through air spaces, spread through air spaces characteristics (micropapillary, solid nest, or single cell), average density (number per slide), and farthest distance from tumor at which spread through air spaces was detected, or maximal spread distance. Overall survival and recurrence-free survival were estimated using Kaplan-Meier curves, and differences between spread through air spaces positive versus spread through air spaces negative groups were assessed using the log-rank test.

Results: Spread through air spaces was present in 389 of 787 of the reviewed cases (49.4%). Overall survival and recurrence-free survival were significantly lower in the spread through air spaces positive group over 10 years (P < .0001). The incidences of locoregional and distant recurrence were nearly doubled over 10 years in the spread through air spaces positive group compared with the spread through air spaces negative group (P = .002 and <.0001, respectively). In a multivariable Cox regression model adjusted for spread through air spaces characteristics, distance, and tumor size, lobar resection did not confer survival advantage in patients with spread through air spaces (hazard ratio of sublobar resection with respect to lobar resection, 1.44; 95% confidence interval, 0.98-2.11; P = .067). In the spread through air spaces positive group, spread through air spaces density was 2.7 ± 1.4 clusters per slide and the maximal spread distance was 2.2 ± 1.7 mm from the tumor edge. There was no observed correlation between spread through air spaces density or maximal spread distance and overall survival or recurrence.

Conclusions: We show increased distant recurrence in spread through air spaces positive lung adenocarcinoma. Quantifiable measures of spread through air spaces do not appear to correlate with recurrence or survival metrics.