Sites of metastasis and overall survival in esophageal cancer: a population-based study

BACKGROUND: There are few population-based studies of the sites of distant metastasis (DM) and survival from esophageal cancer (EC). The aim of this study was to assess the patterns and survival outcomes for site-specific DM from EC using a population-based approach. METHODS: Patients diagnosed with de novo stage IV EC between 2010 and 2014 were identified from the Surveillance, Epidemiology, and End Results program database. Overall survival (OS) was compared according to the site of DM. RESULTS: We included 3218 patients in this study; the most common site of DM was the liver, followed by distant lymph nodes, lung, bone and brain. Median OS for patients with liver, distant lymph node, lung, bone, and brain metastases was 5, 10, 6, 4, and 6 months, respectively (p<0.001). Site and number of distant metastases were independent prognostic factors for OS. In patients with a single site of DM, using liver metastases as reference, OS was lower for bone metastases (p=0.026) and higher for distant lymph node metastases (p=0.008), while brain (p=0.653) or lung (p=0.081) metastases had similar OS compared with liver metastases. Similar site-specific survival differences were observed in the subgroup with esophageal adenocarcinoma. However, distant lymph node metastases was associated with better survival (p=0.002) compared to liver, bone, or lung metastases in esophageal squamous cell carcinoma. CONCLUSION: Site of metastasis affects survival in metastatic EC; OS was worst for bone metastases and greatest for distant lymph node metastases.