OBJECTIVETo analyze the data of patients with clinical stage T1a lung adenocarcinoma and find the predictive factors associated with lymph node metastasis.

METHODSFrom January to June 2012, 271 patients with small nodules of peripheral lung adenocarcinoma were enrolled in the retrospective review. There were 105 male and 112 female patients, with an average age of (61 ± 11)years (range 32-85 years). The data were collected including age, gender, smoking history, carcinoembryonic antigen(CEA), imaging findings, surgical procedure, pleural involvement, symptoms, tumor size, pathological classification, pathologic stage, maximum standardized uptake value(SUVmax) and lymph node metastasis. The predictive factors of lymph node metastasis in clinical factors were detected by univariate and multivariate analysis.

RESULTSBy preoperative thin-section CT, 35 patients were categorized as pure ground-grass opacity(GGO), 11 cases of atypical adenomatous hyperplasia, 24 cases of adenocarcinoma in situ, with no lymph node metastasis. Categorized as mixed ground-glass opacities in 89 patients, 84 patients (94.4%) had no lymph node metastasis, only 5 patients (6.0%) with lymph node metastasis. Categorized as solid nodules in 93 patients, a total of 28 cases (30.1%) had lymph node metastasis. There were statistically significant difference between three groups (χ(2) = 23.41, P < 0.001) . By univariate analysis, we found that the predictive factors of lymph node metastasis were as follows: tumor size > 1 cm (χ(2) = 9.021, P < 0.003) , imaging performance with mixed GGO or solid nodules (χ(2) = 23.41, P < 0.000) , CEA > 5 µg/L (χ(2) = 15.541, P < 0.000) and PET-CT SUVmax > 5 (χ(2) = 0.644, P < 0.000). By multivariate analysis, we found that imaging performance (mixed GGO or solid nodules) was the independent predictor of lymph node metastasis in clinical factors (OR = 166.116, 95%CI:18.161-25.19, P < 0.001) .

CONCLUSIONSPatients of pure GGO generally do not have lymph node metastasis. Tumor diameter > 1 cm, imaging findings with the mixed GGO or solid nodules, carcinoembryonic antigen CEA > 5 µg/L, PET-CT SUVmax > 5 are predictive factors of lymph node metastasis in which imaging is independent predictor.