Association between the presence of solid or micropapillary components and survival outcome in stage ⅠA lung adenocarcinoma cases: a retrospective cohort study

Abstract

Objectives: To examine the influence of the proportion of pathological subtypes on the prognosis of stage ⅠA lung adenocarcinoma cases, and to explore the association between the presence/absence of solid or micropapillary (S/M) components and survival outcome. Methods: Totally 321 patients with stage ⅠA lung adenocarcinoma who received complete surgical resection at Department of Thoracic Surgery, Tongji University Affiliated Shanghai Pulmonary Hospital from January 2011 to December 2013 were retrospectively analyzed. There were 130 males and 191 females, aging 59(11) years (M(IQR)) (range: 55 to 66 years). The diagnostic value of the proportion of each pathological growth subtype on relapse-free survival (RFS) and overall survival (OS) were analyzed by using receiver operator characteristic curve. Patients were firstly divided into two groups according to the presence or absence of S/M components. And patients without S/M components were farther divided into two groups according to predominant growth pattern. There were three groups in total: with S/M components (group S/M+), without S/M components and lepidic growth pattern predominant (group S/M-LPA), without S/M components and papillary or acinar growth pattern predominant (group S/M-P/A). Kaplan-Meier method were used to draw the survival curves of the three groups, and Log-rank test were used to compare RFS and OS among the three groups. Cox proportional risk model was used to verify whether the presence of S/M components was a prognostic factor on RFS. Results: The proportion of S/M components had no diagnostic value for recurrence (solid: area under curve (AUC)=0.588, P=0.095; micropapillary: AUC=0.566, P=0.106) and death (AUC=0.589, P=0.104; AUC=0.607, P=0.056). The 5-year RFS rate of group S/M-LPA, S/M-P/A and S/M+ were 92.4%, 82.3% and 77.3%, respectively (all P<0.05), while the 5-year OS rate were 97.4%, 94.5% and 83.2%, respectively (all P<0.05). Multivariable analysis showed that the 3 groups were independent predictors of recurrence (S/M-P/A vs. S/M- LPA: HR=2.691, 95%CI: 1.249 to 5.799, P=0.011; S/M+ vs. S/M-LPA, HR=6.763, 95%CI: 3.050 to 14.996, P<0.01). Conclusions: The proportion of S/M components in stage ⅠA lung adenocarcinoma with complete resection cases did not affect survival outcome. New grouping method based on the presence or absence of S/M components were significantly associated with patient survival outcomes: S/M+ patients had the worst prognosis and S/M-LPA patients had the best prognosis.