title: Recognition of "aggressive" behavior in "indolent" ground glass opacity and mixed density lesions.
abstract: BACKGROUND
  Radiologically characteristic ground-glass opacity (GGO) represents a special cohort of pulmonary adenocarcinomas that has been unanimously defined as biologically inert. Lymph node metastasis, however, occurs occasionally in these biologically "indolent" cancers. The incidence and underlying risk factors of nodal metastasis remain unknown.
  
  
  METHODS
  All surgically removed GGO lesions between January 2008 and December 2014 were retrospectively reviewed from a single treatment institution. Pathologically-confirmed adenocarcinomas with systemic lymph node dissection or sampling were enrolled into the present study. All the lesions were classified into three groups according to the proportion of solid densities: group I, pure GGO; group II, 1% to 50%; and group III, 50% to 79%. Risk factor analysis of lymph node involvement was performed by multivariate logistic regression.
  
  
  RESULTS
  Of the 867 patients eligible for this study, 553 (63.7%) presented as pure GGOs (Group I) and 314 (36.2%) were mixed GGOs, of which 160 (18.5%) were in group II and 154 (17.8%) in group III. Lymph node metastasis was confirmed in 25 patients, among these 25 cases, 11 (11/160) were group II and 14 (14/154) were group III; two of the 25 patients died from lung cancer metastases at their postoperative 23(rd) and 36(th) month, respectively. Statistical analysis revealed three predictors for lymph nodal metastasis: tumor size, preoperative serum carcinoembryonic antigen level and proportion of the mix density.
  
  
  CONCLUSIONS
  A larger size, mixed GGOs with a higher proportion of solid component, and elevated serum CEA level were associated with a higher preference for nodal metastasis.
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Junyan
authors: J
authors: Zha
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Dong
authors: D
authors: Xie
authors: Department of Pathology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Huikang
authors: H
authors: Xie
authors: Department of Pathology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Liping
authors: L
authors: Zhang
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Fangyu
authors: F
authors: Zhou
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Pengqing
authors: P
authors: Ying
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Lilan
authors: L
authors: Zhao
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Gening
authors: G
authors: Jiang
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Ke
authors: K
authors: Fei
authors: Department of Thoracic Surgery, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200082, China.
authors: Chang
authors: C
authors: Chen
keywords: Ground-glass opacity (GGO); lymph node metastasis; non-small-cell lung cancer