Objective To evaluate the role of elastic fiber changes in predicting survival outcomes in intermediate-grade lung adenocarcinoma.Methods All pulmonary adenocarcinoma resections conducted between January 2009 and December 2009 were reviewed.Pathologically confirmed adenocarcinomas smaller than 3 cm were included in the present study.All cases were categorized into three elastic fiber patterns (EFP):complete loss as pattern Ⅰ (EFP Ⅰ),partial loss as pattern Ⅱ (EFP Ⅱ),normal and diffusely increase as pattern Ⅲ (EFP Ⅲ).Patients with different EFP were compared.Results One hundred and ninety four patients were included in this study,with 67 (34.5％),70 (36.1％) and 57 (29.4％) cases presenting as EFP Ⅰ,EFP Ⅱ,and EFP Ⅲ,respectively.Lymph nodal metastases occurred in 35.8％ (24/67),40.0％ (28/70),and 10.5％ (6/57) of EFP Ⅰ,EFP Ⅱ and EFP Ⅲ patterns,respectively.The percentage of EFP Ⅰ and Ⅱ increased with increasing tumor size,these patterns occurring in 55.1％ (38/69) of tumors ≤2.0 cm,and 79.2％ (99/125) of tumors 2.1-3.0 cm in sizes,respectively.The overall 5-year overall survival rate was 75.8％,and 67.2％ for EFP Ⅰ,68.6％ for EFP Ⅱ,and 94.7％ for EFP Ⅲ.Conclusion In patients with intermediate-grade lung adenocarcinoma,EFP should be formally recognized as a feature of tumor invasion,and its evaluation can help to recognize tumor invasive and access clinical prognosis.