Objective: The aggressiveness of small adenocarcinomas has not been fully evaluated using integrated positron emission tomography/computed tomography. We investigated malignant aggressiveness according to positron emission tomography/computed tomography, high-resolution computed tomographic findings, and the proportions of pathologically defined bronchioloalveolar carcinomas in cT1N0M0 lung adenocarcinoma.
Methods: Sixty consecutive patients with cT1N0M0 lung adenocarcinomas of 3 cm or less in diameter underwent fluorodeoxyglucose-positron emission tomograph/computed tomography, and high-resolution computed tomography, followed by complete tumor resection. Correlations between the proportion of bronchioloalveolar carcinoma and maximum standardized uptake value on positron emission tomographic scan/computed tomographic scan, ground-glass opacity, and tumor shadow disappearance rate were investigated and the findings were compared with clinicopathologic features.
Results: Lymphatic and vascular invasion occurred in 18 (30%) and 13 (22%) patients, respectively, whereas hilar or mediastinal lymph nodes occurred in 8 patients (13%). Maximum standardized uptake value generally seemed the most valuable predictor of lymphatic invasion, vascular invasion, and nodal metastasis compared with ground-glass opacity, tumor shadow disappearance rate, and bronchioloalveolar carcinoma ratios. Although the association was significant between the bronchioloalveolar carcinoma ratio versus maximum standardized uptake value, ground-glass opacity ratio, and tumor shadow disappearance rate (all P < .0001), maximum standardized uptake value (R2 = 0.245) was less correlated with the bronchioloalveolar carcinoma ratio than was the ground-glass opacity ratio (R2 = 0.554) and tumor shadow disappearance rate (R2 = 0.671).
Conclusions: The malignant behavior of small adenocarcinomas with a lower maximum standardized uptake value and a greater proportion of ground-glass opacity, tumor shadow disappearance rate, and bronchioloalveolar carcinoma was less aggressive. Maximum standardized uptake value was a more powerful clinical predictor of biologic tumor performance, independent of pathologic bronchioloalveolar carcinoma proportion. Preoperative assessment of maximum standardized uptake value on positron emission tomographic/computed tomographic findings, in addition to the ground-glass opacity ratio and tumor shadow disappearance rate on high-resolution computed tomographic scans, might be useful to guide treatment strategies for small adenocarcinomas.