Fig. 1

Low expression of pro-SFTPB is associated with progression of early-stage lung adenocarcinoma (LUAD). a pro-SFTPB expression in the primary tumors of patients with early-stage LUAD and in the tissues adjacent to these tumors was measured by immunohistochemistry (n = 160). b-d Low expression of pro-SFTPB compared to the adjacent tissue correlated with high recurrence (b), lower recurrence-free survival (c), and lower overall survival in patients with early-stage LUAD (n = 160) (d). e Patients with early-stage LUAD whose serum pro-SFTPB concentrations were within the range of concentrations (measured as mean ± SEM) found in healthy individuals were placed in the normal pro-SFTPB group, and patients whose serum pro-SFTPB concentrations fell below that range were placed in the low pro-SFTPB group. f-g Kaplan‒Meier survival analysis showed that low levels of serum pro-SFTPB were closely correlated with lower recurrence-free survival (f) and lower overall survival of patients with early-stage LUAD (g). P values were calculated using the log-rank test. MTR, median time of recurrence; MST, median time of survival