IASLC and WHO 2004 Grading System as Prognostic Factors in 492 Cases of Pulmonary Adenocarcinoma

Background: Primary aim of the study was to evaluate the prognostic value of the IASLC grading system and the WHO 2004 classification on a consecutive series of resected primary pulmonary adenocarcinomas. Secondary aim was to identify new prognostic histological features. Methods: All consecutive patients undergoing radical resection with a pathological diagnosis of primary lung adenocarcinoma were considered. All histological slides were reviewed for the study. Tumor-specific survival was considered as primary outcome. Statistical analysis included Kaplan-Meyer analysis and Cox regression to identify variables with significant Hazard Ratios (HR). Results: 492 patients were considered between January 2002 and December 2013. 67.7% were male, mean age was 67.4 years, mean follow-up was 55 months. In a first multivariate Cox Regression Model the WHO 2004 grading was considered; gender [males vs females HR=1.7 95% CI (1.2-2.3), p=0.002], stage (p-trend <0.001), lymphoplasmacellular infiltrate [yes vs no HR=0.5 95% CI (0.3-0.8), p=0.001], and WHO 2004 grade (p-trend = 0.002) were independent prognostic factors of survival. In a second model the IASLC grading was considered; gender [HR=1.7 95% CI (1.2-2.4), p=0.002], stage (p-trend<0.001), lymphoplasmacellular infiltrate [HR=0.5 95% CI (0.3-0.8), p=0.001], and combined grading score according to Sica (p-trend=0.011) were maintained as independent prognostic factors. Conclusion: Tumor grading was an independent prognostic factor of survival in patients with adenocarcinoma undergoing lung resection both considering IASLC and WHO 2004 classifications. Lymphoplasmacellular infiltrate was significantly and favorably related to survival.