Sites of distant metastases and the cancer-specific survival of metastatic Siewert type II esophagogastric junction adenocarcinoma: a population-based study.

Background: The effect of distant metastasis on prognosis in patients with Siewert type II adenocarcinoma of the esophagogastric junction (AEG) remains elusive. Methods: Patients diagnosed as metastatic Siewert type II AEG were identified using the Surveillance, Epidemiology, and End Results (SEER) database. Kaplan-Meier survival analysis and a Cox proportional hazards analysis were performed to assess the effect of distant metastases sites. Results: We analyzed 1616 eligible patients. Liver was the most frequent metastatic site. For patients with isolated distant metastasis, the median survival time was 8, 7, 8, 10, and 11 months for patients with liver, bone, brain, lung, and distant lymph nodal metastasis, respectively (p = 0.011). The number of metastatic sites and the site of distant metastasis were independent prognostic factors for cancer-specific survival (CSS). In patients with isolated distant metastasis, using bone metastasis as reference, lung (p = 0.011) or distant lymph node metastasis (p = 0.030) was associated with better CSS, while patients with liver (p = 0.051) or brain (p = 0.488) metastasis had similar CSS compared to patients with bone metastasis. Conclusion: CSS in metastatic Siewert type II AEG is dependent on the metastatic site and the number of metastatic sites.