Micropapillary and solid subtypes of invasive lung adenocarcinoma: Clinical predictors of histopathology and outcome

Objective To evaluate the clinical effect of the presence of a micropapillary or solid subtype on the outcomes in lung adenocarcinoma and to determine the predictors of such a histopathologic diagnosis. Methods A total of 511 patients with lung adenocarcinoma ≤3 cm were included. According to the presence of micropapillary or solid subtypes, we classified the patients into 4 subgroups: both subtypes absent (MP−/S−, n = 87), either subtype present (MP+/S−, n = 207 and MP−/S+, n = 196), and both present (MP+/S+, n = 21) to determine the association between the micropapillary or solid subtype and survival outcome or clinical and imaging conditions. Univariate and multivariate analyses were undertaken to determine the parameters, allowing the prediction of the presence of the micropapillary or solid subtype. Results Overall survival (OS) and disease-free survival (DFS) differed significantly among the 4 subgroups ( P