Comparison of clinical results between high grade patterns in stage I lung adenocarcinoma

Background: The histological subtype has been introduced in invasive lung adenocarcinoma. The predominant micropapillary and solid subtypes are categorized as high-grade patterns and provide a worse prognosis. However, the prognostic analysis of high-grade patterns has not previously been fully investigated. Thus, this study aimed to investigate the prognostic role of high-grade patterns in pathological stage I lung adenocarcinoma. Methods: Patients with stage I lung adenocarcinoma and micropapillary or solid components were reviewed. Clinicopathological features and clinical course were compared in these subtypes, and prognostic factors were analyzed in high-grade patterns. Results: The patients were classified into five groups based on the presence of micropapillary or solid subtypes, namely, micropapillary predominant, solid predominant, both nonpredominant subtypes, only minor micropapillary subtype, and only minor solid subtype present. Disease-free interval was significantly different, and the micropapillary predominant group showed worse disease-free interval (p = 0.001). Contrastingly, the solid predominant group showed significantly worse overall survival among high-grade patterns (p = 0.035). The multivariate analysis revealed an association between smoking, micropapillary predominant, blood vessel invasion, and visceral pleural invasion with recurrence and more association between solid predominant and visceral pleural invasion with overall survival. Conclusions: Clinical results were different in stage I high-grade adenocarcinoma. The predominant micropapillary subtype is the independent prognostic factor for recurrence. However, the solid subtype is the significant factor for overall survival. Furthermore, the predominant subtype is the most valuable and independent prognostic factor for predicting recurrence or survival.