Survival and Patterns of Failure in Oligometastatic Esophagogastric Cancer

Abstract

Metastatic esophagogastric cancer (EGC) has poor outcomes, with median overall survival (OS) of 9-11 months. Studies in other sites such as lung have shown improved survival with local treatment for oligometastasis (OM). However, there is very limited data on oligometastatic EGC. We investigated outcomes, prognostic factors, and patterns of first progression in patients with oligometastatic EGC. From 2008-2018, 1438 patients (pts) presented to our institution with stage IV EGC. Of these, 197 pts had OM (defined as ≤5 metastatic lesions, excluding primary) and were included for analysis. Median age was 67 years and most (77%) were male. 46 pts (23%) had gastric (GC) and 151 (77%) had esophageal/GE junction (GEJ) tumors. First progression was classified as limited to initial sites, new sites, or failure at both initial and new sites. OS was stratified by primary tumor site, number of OM, and sites of OM using Kaplan Meier and log rank tests. Cox proportional hazards model was used to investigate correlation between prognostic factors and outcomes. At a median follow up of 22.5 (1-117) months, median OS for the whole cohort was 25 months (95%CI: 22.6-27.4) with a statistically significant difference between GC and GEJ cancer (37 vs. 25 months, p = 0.03). Location of OM was as follows: non-regional nodes (44%), liver (17%), peritoneal nodules (7%), bone (6%), lungs (4%), brain (2%), liver plus non-regional nodes (5%), and other (15%). Peritoneal nodules were more common in GC whereas bone, lungs, and brain were more common in GEJ cancer. Most pts had a solitary OM (42.6%). The number or sites of OM did not correlate with OS. Of 152 pts who progressed, 91 (60%) had isolated initial site failure, 17% had isolated new site failure, and 23% had both initial and new site failure. 13% and 10% of pts underwent surgery for primary site and OM respectively. Radiation therapy (RT) to primary site (median 37.5 Gy in 15 fractions), was delivered to 37%, usually upon progression (57%). 11% received RT to OM. On univariate analysis, gastric primary, younger age, primary tumor or OM resection, RT to the primary, and isolated initial site failure were significantly associated with better OS. On multivariate analysis, age (HR: 1.031, p = 0.001) surgery to the primary (HR: 0.295, p = 0.002), and initial-site failure (HR: 1.4 p = 0.002) remained significantly correlated with OS. We observed a longer OS for oligometastatic EGC, compared to historical results for general metastatic disease reported in the literature. This suggests that EGC patients with OM are a prognostically distinct group and may benefit from tailored treatment strategies such as ablative local therapy. Most patients first progressed in their initial sites of disease, suggesting a role for local therapy earlier in the treatment course. Younger patients and those undergoing primary tumor resection had superior OS.