Evaluation of grading systems among pulmonary adenocarcinomas: architectural grade combined with STAS is superior to others - a single centre study

Several grading methods had been proposed for pulmonary adenocarcinomas in the past decades. We aimed to evaluate and compare the prognostic performance of these grading schemes on overall survival (OS) and recurrence-free survival (RFS) in a single center study. Our retrospective study included patients diagnosed with lung adenocarcinoma who underwent surgery between 2010 and 2016 at the clinic of Szeged. Morphological patterns were recorded and revised on histological slides. As statistical analyses, Cox proportional hazard models, Kaplan-Meier analyses, log rank test and ROC analyses were applied. Altogether 304 patients were included in our study. In multivariate analysis of OS, type of surgery (HR:1.81, 95%CI:1.08-3.02, p = 0.025), architectural grade combined with spread through air spaces (STAS) (HR:4.38, 95%CI:1.88-10.20, p < 0.001), lymphovascular (HR:1.87, 95%CI:1.13-3.09, p = 0.014), and vascular spread (HR:2.07, 95%CI:1.00-4.25, p = 0.049) were independent prognostic factors. In multivariate analysis of RFS, stage (HR:2.84, 95%CI:1.42-5.67, p = 0.003) architectural grade combined with STAS (HR:3.13, 95%CI:1.70-5.32, p < 0.010) and vascular spread (HR:2.42, 95%CI:1.31-4.48, p = 0.005) proved to be independent prognosticators. In a subgroup analysis excluding the adverse factors the architectural grade combined with STAS preserved its prognostic impact on OS and RFS. Most grading systems of pulmonary adenocarcinoma take into consideration the architectural features; however, some of them focus on nuclear features or STAS. We have compared the available grading systems and have proven that almost all of them have prognostic role on survival. The architectural grade combined with STAS was superior to others even in subgroup analysis where adverse factors were omitted.