Prognostic impact of noninvasive areas in resected pathological stage IA lung adenocarcinoma

Main Problems: In non-small-cell lung cancer, ground-glass opacity on computed tomography imaging reflects pathological noninvasiveness and is a favorable prognostic factor. However, the significance of pathological noninvasive areas (NIAs) has not been fully revealed. In this study, we aimed to elucidate the prognostic impact of NIAs on lung adenocarcinoma. Methods: We analyzed 402 patients with pathological stage (p-Stage) IA lung adenocarcinoma who underwent surgery in 2013–2016 at two institutions and examined the association of the presence of NIAs with clinicopathological factors and prognosis. Furthermore, after using propensity-score matching to adjust for clinicopathological factors, such as age, sex, smoking history, pathological invasive area size, pathological T factor (p-T), p-Stage, and histological subtype (lepidic predominant adenocarcinoma [LPA] or non-LPA), the prognostic impact of NIAs was evaluated. Results: Patients were divided into NIA-present (N = 231) and NIA-absent (N = 171) groups. Multivariable analysis showed that NIA-present was strongly associated with earlier p-T, earlier p-Stage, LPA, and epidermal growth factor receptor mutation. Kaplan–Meier survival analysis showed that the NIA-present group displayed a better prognosis than the NIA-absent group in disease-free survival (DFS) and overall survival (OS) (5-year DFS 94.6% vs. 87.2%, 5-year OS 97.2% vs. 91.1%). However, after adjusting for clinicopathological factors by propensity score matching, no significant differences in prognosis were identified between the NIA-present and NIA-absent groups (5-year DFS 92.4% vs 89.6%, 5-year OS 95.6% vs 94.3%). Conclusions: Our current study suggests that the prognostic impact of the presence of NIAs on lung adenocarcinoma is due to differences in clinicopathological factors.