Diffuse-Type Histology Is Prognostic for All Siewert Types of Gastroesophageal Adenocarcinoma

The optimal treatment for gastroesophageal junction adenocarcinoma (GEJA) remains controversial. We evaluated the treatment patterns and outcomes of patients with locally advanced GEJA according to the histological type. We conducted a single-institution retrospective cohort study of patients with locally advanced GEJA who underwent curative-intent surgical resection between 2010 and 2020. Perioperative therapies as well as clinicopathologic, surgical, and survival data were collected. The results of endoscopy and histopathological examinations were assessed for Siewert and Lauren classifications. Among the 58 patients included in this study, 44 (76%) were clinical stage III, and all received neoadjuvant therapy (72% chemoradiation, 41% chemotherapy, 14% both chemoradiation and chemotherapy). Tumor locations were evenly distributed by Siewert Classification (33% Siewert-I, 40% Siewert-II, and 28% Siewert-III). Esophagogastrectomy (EG) was performed for 47 (81%) patients and total gastrectomy (TG) for 11 (19%) patients. All TG patients received D2 lymphadenectomy compared to 10 (21%) EG patients. Histopathological examination showed the presence of 64% intestinal-type and 36% diffuse-type histology. The frequencies of diffuse-type histology were similar among Siewert groups (37% Siewert-I, 36% Siewert-II, and 33% Siewert-III). Regardless of Siewert type and compared to intestinal-type, diffuse histology was associated with increased intraabdominal recurrence rates (P=0.03) and decreased overall survival (hazard ratio, 2.33; P=0.02). With a median follow-up of 31.2 months, 29 (50%) patients had a recurrence, and the median overall survival was 50.5 months. Present in equal proportions among Siewert types of esophageal and gastric cancer, a diffuse-type histology was associated with high intraabdominal recurrence rates and poor survival. Histopathological evaluation should be considered in addition to anatomic location in the determination of multimodal GEJA treatment strategies.