Clinical significance of oligometastatic esophageal squamous cell carcinoma: A retrospective cohort study.

391 Background: Oligometastatic disease (OMD) has been proposed as an intermediate state between localized and extensive metastatic cancer, where local therapies may improve outcomes. In esophageal squamous cell carcinoma (ESCC), the definition of OMD, prognostic significance of OMD, as well as the benefit of curative-intent local therapy are not well defined. Methods: We retrospectively reviewed 63 patients with pathologically confirmed metastatic ESCC diagnosed at National Taiwan University Hospital between 2006–2016. Patients with synchronous double cancers were excluded. OMD was defined using OMEC criteria as either (1) ≤3 metastases in a single organ or (2) one extra-regional lymph node station. Clinical variables, treatment modalities, and outcomes were analyzed. Survival was estimated by Kaplan–Meier and compared using log-rank tests. Results: Among 63 patients, 26 (41%) had OMD. Median overall survival (OS) was significantly longer for OMD versus non-OMD (20.8 vs 8.8 months, p