Sa1240 PREDICTORS FOR LYMPH NODE METASTASIS OF T1B ESOPHAGEAL CANCER AND SURVIVAL FOLLOWING ENDOSCOPIC THERAPY WITH/WITHOUT ADJUVANT THERAPY AND SURGERY: AN ANALYSIS OF SURVEILLANCE, EPIDEMIOLOGY, AND END RESULTS (SEER) DATABASE

Abstract

Endoscopic therapy (ET) has become a treatment of choice for high grade dysplasia and intramucosal (T1a) esophageal cancer (EC). For T1b EC (tumor invading submucosa), esophagectomy remains the mainstay treatment because previous studies, using single-centered data, reported higher risk of lymph node metastasis (LNM). The use of ET in low risk T1b EC and ET followed by adjuvant chemotherapy ± radiation (CRT) for patients who decline or are unfit for surgery have been reported. However, outcomes data have been limited to a few small studies from tertiary centers. 1) to determine the prevalence and risk factors of LNM of T1b EC using a large national cancer database and 2) evaluate the survival outcomes of T1bN0M0 EC after ET alone, ET+CRT compared to radical surgery. We used the SEER 18 database to identify patients with T1b histologically confirmed EC diagnosed between 1998-2016. Prevalence of LNM at initial diagnosis and its risk factors were analyzed. Cancer-specific survival (CSS) and overall survival (OS) were calculated using Kaplan-Meier’s (KM) estimate. The multivariate analysis was performed with the Cox-regression method after controlling for other relevant covariates. A total of 1374 patients with T1b EC were identified (mean age: 65; 82% men; 89% white; 77% adenocarcinoma[AC]; 22% squamous cell cancer[SCC]) (Table 1).Overall, 283 patients(20.6%) had LNM at the time of diagnosis with prevalence of 20% in AC and 22.8% in SCC(p=0.279). In multivariate analysis, age≦65, diagnosis in 2010-2016(vs older years), tumor size ≧ 2 cm, and poorly differentiation were associated with LNM. Survival of patients with T1b with LNM was significantly lower than those with LNM(-) [3-yr OS: 63.7% and 47.8%, p<0.001; 3-yr CSS: 72.1% and 54.1%, p<0.001]. Subgroup of patients with T1bN0M0 EC who received ET only(n=96), ET+CRT(n=22) and surgery(n=788) were further analyzed. The median follow-up time was 39 months(IQR 14-89). 3-yr OS and CSS were: 65%/81% in ET, 30%/88% in ET+CRT and 73%/79% in surgery. KM curves are shown in Figure 1. In a multivariate proportional hazards model; adjusted for age, gender, race, histologic type, year of diagnosis, site of cancer, SEER region, ET alone and surgery resulted in statistically equivalent in overall mortality[Hazard ratio(HR) 0.93, 95%CI 0.68-1.43, p=0.93] and esophageal cancer mortality[HR 1.47, 95%CI 0.86-2.51, p=0.16]. ET+CRT, as compared to ET alone, was associated with increased overall mortality[HR 2.17, 95%CI 1.03-4.57, p=0.04], with no significant difference in esophageal cancer survival. In this population-based study, the prevalence of LNM in T1b EC is 20%. In patients with T1bN0M0, overall and cancer specific survival of those treated with ET appears to be similar to those treated with surgery. Addition of CRT following ET negatively impacts survival outcomes.Figure 1Kaplan–Meier graphs showing the survival in patients with T1bN0M0 esophageal cancer treated with endoscopic treatment +/- chemoradiation or surgeryView Large Image Figure ViewerDownload Hi-res image Download (PPT)