Predilection of contralateral upper lung metastasis in upper lobe lung adenocarcinoma patients

Background: Lung cancer with lung to lung metastasis is common. The objective of this study was to investigate the association among the distribution of contralateral lung metastases versus primary lung tumor location, clinical characteristics, and epidermal growth factor receptor (EGFR) mutations status. Methods: The study included treatment-na?ve stage IV lung adenocarcinoma with contralateral lung metastases from 2012 through 2013. Results: In total, 103 patients were enrolled after excluding lung cancer with histology other than adenocarcinoma, synchronous multiple primary lung cancers, or other active malignancy. The median age was 65 years (range, 28-93 years); 47 male patients (45.6%); 69 non-smoker (NS) patients (67.0%); 68 Eastern Cooperative Oncology Group performance status (ECOG PS) 0-1 patients (66.0%); 38 M1a patients (38.9%); and 60 EGFR mutation patients (58.3%). There were 51 cases (49.5%) with primary lung cancer located over upper lobes. Among them, 36 (70.6%) had contralateral upper lung predominance metastasis, 9 (17.6%) had lower lung predominance, and 6 (11.8%) had equal distribution. Among the 52 lower lobe tumors, 17 (32.7%), 19 (36.5%), and 16 (30.8%) had upper, lower lung predominance, and equal distribution metastasis, respectively. Univariate analysis showed only male gender and primary tumor location over upper lobes were significantly associated with contralateral upper lung predominance metastases. After multivariate analysis, only primary tumor location over upper lobes was significantly associated with contralateral upper lung predominance metastases (adjusted OR 5.49, 95% CI, 2.15-14.03, P < 0.001). Conclusions: Upper lobe lung adenocarcinoma was significantly associated with contralateral upper lung predominance metastases. Further research is needed to elucidate the mechanisms underlying this phenomenon. ? Journal of Thoracic Disease. All rights reserved.