The prognostic and predictive value of solid subtype in invasive lung adenocarcinoma

A total of 1039 stage I-III invasive lung adenocarcinoma including 186 solid subtype patients who have undergone radical resection were assessed for clinicopathologic characteristics, status of common driver mutations, pattern of recurrence, recurrence-free survival (RFS), overall survival (OS), post-recurrence survival (PRS) and predictive value for adjuvant chemotherapy and EGFR tyrosine kinase inhibitors (TKIs). Solid predominant adenocarcinomas were more likely to have initial distant recurrences than non-solid subtype invasive adenocarcinomas (P = 0.018). In univariate analysis, solid predominant adenocarcinoma patients had significantly worse RFS (P < 0.001), OS (P < 0.001) and PRS (P = 0.010). Multivariate analysis adjusting for clinicopathologic variables and mutational status showed that solid subtype was an independent poor prognostic factor (odds ratio = 1.876, 95% confidence interval: 1.291-3.158; P = 0.003) and an independent negative predictor for stage II-III patients undergoing adjuvant chemotherapy (odds ratio = 2.020, 95% confidence interval: 1.291-3.158; P = 0.002). In EGFR-mutated solid predominant lung adenocarcinoma patients who experienced disease recurrence, the response rate to EGFR TKIs was only 37.5%. In radically resected invasive lung adenocarcinoma, solid subtype was an independent poor prognostic factor and negative predictor for adjuvant chemotherapy.