Survival outcome of metastatic adenocarcinoma of esophagogastric junction in the trastuzumab era.

Abstract

117 Background: Previous studies have reported no differences in treatment outcomes between metastatic adenocarcinoma esophagogastric junction (AEGJ) and gastric adenocarcinoma (GAC). However, after the approval of trastuzumab (Tmab) for the treatment of metastatic AEGJ and GAC survival outcomes remain unclear. Methods: We retrospectively reviewed clinicopathological characteristics, treatment outcomes, and prognoses of 289 consecutive patients with AEGJ and GAC who received first-line chemotherapy from March 2011, when Tmab was approved in Japan, to December 2013 at Aichi Cancer Center Hospital. Prognostic factors were identified using Cox multivariate regression analysis. IHC3+ or IHC2+/ISH+ tumors were defined as HER2 positive. Results: Of 289 patients, 45 (16%) had AEGJ. Patients with AEGJ were significantly younger with lesser lung metastases than those with GAC. HER2-positive rates in AEGJ tended to be greater than those in GAC, but this difference was not statistically significant (22% vs. 16%; P = 0.35). The rates of platinum doublet therapies were not significantly different (72% vs. 78%; P = 0.47). The objective response rate (ORR) was 27% with AEGJ and 40% with GAC (P = 0.17). The median follow-up duration was 12.1 and 11.9 months, respectively. Progression-free survival was similar for both the groups [hazard ration (HR) = 0.97; P = 0.83), while the median overall survival (OS) period was numerically longer for AEGJ than that for GC (14.7 vs. 12.4 months; HR = 0.99; 95% confidence interval = 0.69–1.39; P = 0.92). In patients with AEGJ, an ECOG performance status of 2 and HER2 negativity were significantly associated with poor prognosis, as estimated by the multivariate analyses of OS. The analyses that were limited to patients treated with Tmab as the first-line chemotherapy revealed no significant differences in ORR and median OS between AEGJ and GAC. Conclusions: Even in the Tmab era, there were no significant differences in survival outcomes between metastatic EGC and GAC.