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

Abstract

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 <0.001). Patients who received curative-intent local treatment for metastases (surgery, ablation, or radiotherapy) achieved improved OS (20.6 vs 8.9 months, p =0.001) and progression-free survival (PFS, 8.5 vs 5.0 months, p =0.010). Metachronous presentation and limited number of metastatic sites were additional favorable prognostic factors for OS ( p <0.001 and p =0.006, respectively). Type of local treatment and receiving systemic therapy were not independently associated with OS. Two long-term survivors were identified, both with metachronous lung oligometastases successfully resected after definitive chemoradiotherapy and esophagectomy. Conclusions: In this retrospective cohort, OMD and curative-intent local therapy were associated with improved OS and PFS in metastatic ESCC. These findings suggest OMD is a clinically meaningful state in ESCC and supports prospective evaluation of local consolidative strategies in this population.