Factors predicting organ-specific distant metastasis in patients with completely resected lung adenocarcinoma

The aim of the study is to demonstrate the relationship between clinicopathological variables and organ sites of metastasis in resected lung adenocarcinoma. The clinicopathological characteristics of 748 patients of resected lung adenocarcinoma at Taipei Veterans General Hospital between 2004 and 2012 were retrospectively reviewed. The prognostic value of clinicopathological variables for specific organ site metastasis-free survival was demonstrated. Among the 182 patients with distant metastasis, 93 (51.1%) patients developed contralateral lung metastasis, 81 (44.5%) had brain metastasis, 71 (39.0%) had bone metastasis, and 18 (8.9%) had liver metastasis during follow-up. Acinar predominant (Hazard ratio [HR], 0.468; 95% confidence interval [CI]: 0.250 to 0.877; P = 0.018) was significantly associated with less contralateral lung metastasis in multivariate analysis. Micropapillary predominant (HR, 2.686; 95% CI, 1.270 to 5.683; P = 0.010) was significantly associated with brain metastasis. Acinar predominant (HR, 0.461; 95% CI, 0.216 to 0.986; P = 0.046) was a significant prognostic factor for better contralateral lung metastasis-free survival in multivariate analysis. Micropapillary predominant (HR, 2.186; 95% CI, 1.148 to 4.163; P = 0.017) and solid predominant (HR, 4.093; 95% CI, 1.340 to 12.504; P = 0.013) were significant prognostic factors for worse brain metastasis-free survival and liver metastasis free-survival, respectively. There are significant differences in metastatic behavior between predominant pathological subtypes of lung adenocarcinoma. This information is important for patient follow-up strategy and identification of organ-specific distant metastasis. Prospective multi-institutional studies are mandatory for further validation.