Value of CT Characteristics in Predicting Invasiveness of Adenocarcinoma Presented as Pulmonary Ground-Glass Nodules

Background Less invasive adenocarcinomas (LIAs) of the lung, including adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA), are indications of sublobar resection and has a 5‐year disease‐free survival rate of almost 100% after surgery. By distinguishing invasive adenocarcinoma from LIA with computed tomography (CT) characteristics, it is possible to determine the extent of resection and prognosis for patients with ground‐glass nodules (GGNs) before surgery. Methods We reviewed CT and pathological findings of 728 GGNs in 645 consecutive patients who received curative lung resection in a single center. Only AIS, MIA, and invasive adenocarcinoma were included. Characteristics of CT, including maximum diameter of the lesion (Lmax) and maximum diameter of the consolidation (Cmax), were assessed thoroughly. Results Multivariate logistic regression showed that larger Lmax (p < 0.001) and nonsmooth margin (p = 0.001) were independent factors for invasive adenocarcinoma in pure GGNs (pGGNs). The optimal cut‐off value of Lmax was 12.0 mm. In mixed GGNs (mGGNs), multivariate analysis revealed that larger Lmax (p < 0.001), larger Cmax (p = 0.032), and vacuole sign (p = 0.007) were predictive factors for invasive adenocarcinoma, and the area under curve of regression model was 0.866. The optimal cut‐off values of Lmax and Cmax were 15.4 and 5.8 mm, respectively. No node metastasis was found in 295 patients who had at least three stations of mediastinal lymph nodes dissected. Conclusion In pGGNs, larger Lmax (>12.0 mm) and nonsmooth margin were reliable predictors for invasive adenocarcinoma. In mGGNs, lesions with larger Lmax (>15.4 mm), larger Cmax (>5.8 mm), and vacuole sign were more likely to be invasive adenocarcinoma.