A proposal for re-staging of invasive lung adenocarcinoma manifesting as pure ground glass opacity.

Background. Invasive lung adenocarcinoma (IAC) occurs in 22.8% to 40.4% of pure ground-glass opacity (GGO) cases. This study assessed the malignancy and survival outcomes of IAC manifesting as pure GGO with the aim of providing suggestions on T staging of these tumors. Methods. From January 2010 to December 2012, the study focused on 109 cases of IAC that radiologically manifested as pure GGO. For comparison, 305 clinical stage IA part-solid IACs were also included. Clinico-pathological characteristics, managements, and prognoses were evaluated. Results. As compared with part-solid nodules, pure GGOs showed lower T stage, lower N stage, smaller invasive size, less invasive predominant components, and better survival. Long-term outcomes were independently influenced by whether the tumors presented as pure GGO. For the pure GGO group, the 5-year overall and disease-free survival rates were 100% and 99.1%, respectively. The pT stage, invasive size, and predominant component type did not influence survival. Conclusions. IAC radiologically manifesting as pure GGO is a group of tumors with low-grade malignancies and excellent prognosis. External validation is needed to assess whether it should be restaged in the TNM classification of non-small lung cancers. (C) 2019 by The Society of Thoracic Surgeons