Histological classification of lung adenocarcinoma subtype has a prognostic value in most studies. However, lung adenocarcinoma characteristics differ across countries. Here, we aimed at validating the prognostic value of this classification in a large French series of lung adenocarcinoma.
We reviewed 407 consecutive lung adenocarcinomas operated on between 2001 and 2005 and reclassified them according to the IASLC/ATS/ERS classification and subsequently graded into low, intermediate and high grade. We analysed the relevance of this classification according to clinical, pathological, and molecular analysis.
Patients (median age: 61, 288 men) underwent lobectomy (n=378) or pneumonectomy (n=29). Patients overall survival at 5 and 10-year was 53.2% and 32.6%, respectively. UICC stage distribution was 189 stage I, 104 stage II, 107 stage III and 7 stage IV. Low grade tumor was found in 1 patient, intermediate grade in 275 patients and high grade in 131 patients. KRAS and EGFR mutations, were detected in 34% and 9.6% respectively. Histological grade was significantly correlated with extent of resection (P=0.01), TTF-1 expression (P=10-8), vascular emboli (P=0.03) and EGFR mutations (P=0.01). Mucinous adenocarcinomas were associated with KRAS mutations (P=0.003). At univariate analysis, age, extent of resection, histological grade, pleural invasion, vascular emboli, pathological T and N, and stage, were predictive of survival. At multivariate analysis, age (P=10-4), histological grade (P=0.03) and stage (P=3.10-6) were independent prognostic factors.
IASLC/ATS/ERS classification of lung adenocarcinomas predicts survival in French population. Histological grade correlates with clinical, pathological and molecular parameters suggesting different oncogenic pathways.