Neoadjuvant vs. Adjuvant treatment of Siewert type II gastroesophageal junction cancer: An analysis of data from the surveillance, epidemiology, and end results (SEER) registry

Background: Cancer of the gastroesophageal junction (GEJ) has been rising in incidence in recent years. The role of radiation therapy (RT) in the treatment of GEJ cancer remains unclear, as the largest prospective trials advocating for either adjuvant or neoadjuvant chemoradiotherapy (CRT) combine GEJ cancer with either gastric or esophageal cancer. The aim of the present study is to examine the association of neoadjuvant versus adjuvant treatment with overall and disease-specific survival (DSS) for patients with surgically resected cancer of the true GEJ (Siewert type II). Methods: The surveillance, epidemiology, and end results (SEER) registry database (2001-2011) was queried for cases of surgically resected Siewert type II GEJ cancer. A total of 1,497 patients with resectable GEJ cancer were identified, with 746 receiving adjuvant RT and 751 receiving neoadjuvant RT. Retrospective analysis was performed with the endpoints of overall and DSS. Results: Using cox regression and controlling for independent covariates (age, sex, race, stage, grade, histology, and year of diagnosis), we showed that adjuvant RT was associated with a significantly lower death risk [hazard ratio (HR), 0.84; 95% confidence interval 0.73-0.97; P value=0.0168] and significantly lower disease-specific death risk (HR, 0.84; 95% confidence interval, 0.72-0.97; P value=0.0211) as compared to neoadjuvant RT. Conclusions: This analysis of SEER data showed that adjuvant RT was associated with a survival benefit as compared to neoadjuvant RT for the treatment of Siewert type II GEJ cancer. We suggest future prospective studies to compare outcomes of adjuvant versus neoadjuvant treatment for true GEJ cancer.