Primary Tumor Location Is a Useful Predictor for Lymph Node Metastasis and Prognosis in Lung Adenocarcinoma

We examined the value of tumor location in predicting the clinicopathologic features, survival, and metastases of pulmonary adenocarcinoma.

A total of 417 cases of pulmonary adenocarcinoma were included in the present study. The tumors with invasion of the segmental and/or lobar bronchus were classified as central adenocarcinoma and those without as peripheral adenocarcinoma. Histologic grade, cytologic features, and adenocarcinoma type (terminal respiratory unit [TRU] type vs. non-TRU type) were compared between the 2 groups. The prognostic factors for disease-free survival (DFS) were analyzed using univariate and multivariate analyses.

Central adenocarcinoma was associated with lymphatic and/or vascular invasion (P = .011), necrosis (P < .001), high histologic grade (P = .004), and advanced stage (P < .001). For lung adenocarcinoma 1 to 4 cm in size, central adenocarcinoma was linked to a greater rate of nodal metastasis than peripheral adenocarcinoma. However, for lung adenocarcinoma of other sizes, central and peripheral adenocarcinoma had no differences in the rates of nodal metastasis. For nuclear features, central adenocarcinoma showed high mitotic counts, advanced nuclear atypia, and larger nuclei (P < .001, P < .001, P < .001, respectively). More peripheral adenocarcinomas than central adenocarcinomas were TRU type (229 of 281 [81.5%] vs. 58 of 136 [42.6%]; P < .001). Multivariate survival analyses of DFS showed that tumor location (central vs. peripheral, hazard ratio, 1.744; P < .001) was a stage-independent prognostic factor.

Central adenocarcinoma is associated with a high potential for regional lymph node metastases, even at a small size. The results of our study showed that tumor location is an important factor for choosing treatment strategies and predicting DFS.