Lung adenocarcinoma can be subtyped according to tumor dimension by computed tomography mediastinal-window setting. Additional size criteria for clinical T1 adenocarcinoma.

Objective: We sought to verify that the size of the solid component, which can be evaluated using the computed tomography mediastinal-window setting, provides new criteria for CT classification of lung adenocarcinoma.

Methods: Between 1994 and September 2002, we examined 60 patients who were clinically classified with stage T1 adenocarcinoma of the lung and normal serum CEA, who underwent standard surgical procedures. Tumor maximum dimension was evaluated using two different CT-imaging settings: the lung window (lDmax), and the mediastinal window (mDmax). We analyzed the relationships between prognosis or lymph node involvement and tumor dimensions.

Results: The mDmax was a significant (OR 1.11, P=0.02) predictive factor for lymph node metastasis. However, lDmax was not significant (P=0.83). Age, gender, lDmax, mDmax, and lymph node involvement were analyzed as predictive factors for prognosis. In univariate analysis, mDmax and lymph node involvement were significant predictive factors for prognosis (OR 1.07, P=0.01; OR 2.56, P=0.04; respectively). In multivariate analysis, mDmax was a significant predictive factor for prognosis (OR 1.06, P=0.04). We then classified the C-T1 adenocarcinoma patients into three groups according to mDmax: T1a (< or =10 mm), T1b (from 11 to 20 mm), and T1c (from 21 to 30 mm). There was a significant difference between the three groups: the disease-free 5-year survivals were 93.3, 58.1, and 32.7%, respectively (P=0.01).

Conclusions: The mDmax can give additional, useful prognostic data. This finding may provide new criteria for CT classification of lung adenocarcinoma.