Prognostic factors of acinar- or papillary-predominant adenocarcinoma of the lung

Abstract

OBJECTIVE: Histologic types are correlated with prognosis in lung adenocarcinoma. The acinar/papillary type is most common, although this group comprises heterogeneous tumor types. However, the prognostic factors in this group have not been well studied. Therefore, we investigated the prognostic factors of acinar/papillary lung adenocarcinomas and attempted to define the so-called "intermediate grade" group of lung adenocarcinoma.

MATERIALS AND METHODS: We classified surgically resected invasive non-mucinous adenocarcinomas of the lung and analyzed their clinicopathological features and prognostic factors, focusing on the acinar/papillary type.

RESULTS: A total of 301 cases with stage I-III lung adenocarcinoma were enrolled, of which 193 were acinar/papillary type (64.1%). In survival analysis of the entire cohort, acinar/papillary types showed intermediate survival compared with lepidic and micropapillary/solid types. In the univariate survival analysis for acinar/papillary types, stage, age, lymphovascular invasion, spread through air spaces, presence of micropapillary or solid pattern, and programmed death-ligand 1 (PD-L1) positivity were associated with poor recurrence-free survival and overall survival. In multivariate analysis, spread through air spaces and PD-L1 expression were independent poor prognostic factors of recurrence-free survival and overall survival in the acinar/papillary cohort, respectively.

CONCLUSIONS: Evaluation of spread through air spaces and PD-L1 expression may be useful to stratify patients with acinar/papillary lung adenocarcinomas in terms of prognosis.