P0628 - The Differences in the Clinicopathological Features of Early-Stage Adenocarcinomas of the Esophagogastric Junction Between the United States and Japan

Keiko Yamamoto, MD, PhD¹, Yukihiro Nakanishi, MD, PhD¹, Hiroaki Takahashi, MD, PhD², Emi Takakuwa, MD, PhD³, Naoya Sakamoto, MD, PhD³, Schaffer Mok, MD¹, Jose Pimiento, MD¹, Gregory Lauwers, MD¹
1Moffitt Cancer Center, Tampa, FL; 2Keiyukai Hospital, Sapporo, Hokkaido, Japan; 3Hokkaido University, Sapporo, Hokkaido, Japan

Introduction: The incidence of adenocarcinomas of the esophagogastric junction (EGJ) has been increasing in both the United States and Japan. To better understand the pathogenesis of EGJ adenocarcinomas in these two populations, we compared early-stage tumors between American and Japanese patients.

Methods: Internal review board approved analysis of clinicopathological features of 42 American patients (AP) (43 lesions) and 93 Japanese patients (JP) (93 lesions) with Siewert type 1 or 2 and Vienna pathologic diagnosis 4 or 5 treated by endoscopic resection. Statistical differences between both cohorts were defined as p < 0.05.

Results: No significant differences were found in median age in years (68 [34 - 86] vs. 72 [39 - 85]) and male-to-female ratio (34:8 vs. 80:13) for AP and JP. Tumor location (confined within the esophagus/involving the EGJ/confined within the stomach) was found in 21/21/1 in AP vs. 20/36/37 in JP, with gastric location more frequent in JP (p < 0.01). After excluding tumors confined within the stomach, there were no significant differences in the mean tumor size (19.6 ± 9.32 mm vs. 20.0 ± 10.1 mm) and depth of invasion (mucosa/submucosa: 27/15 vs. 43/13) between AP and JP. The distribution of elevated/flat/depressed types was found in 35/7/0 in AP vs. 31/6/19 in JP (p < 0.01), with depressed lesions occurring exclusively in JP. Well or high-grade dysplasia/moderately/poorly differentiated/other tumor types were found in 24/14/4/0 in AP vs. 48/4/1/3 in JP (p < 0.01). Among tumors with submucosal invasion, histologic types in submucosal areas showed a trend toward significance (1/9/3/0 in AP vs. 6/5/1/0 in JP) (p = 0.05). The length of columnar-lined esophagus also differed: long/short/none 18/16/7 in AP vs. 12/37/7 in JP (p = 0.03). While long-segment was more common in AP, JP showed higher Prague C/M values (1.5 ± 2.0/4.7 ± 1.7 in AP vs. 4.7 ± 5.0/8.0 ± 5.3 in JP) (p = 0.02). Intestinal metaplasia showed a trend toward higher prevalence in AP: 30/12 positive/negative in AP vs. 29/27 in JP (p = 0.06). Tumor extension under squamous epithelium was more common in AP (35/6 positive/negative in AP vs. 19/30 in JP) (p < 0.01). Positive horizontal margins occurred exclusively in AP (33/9/0 positive/negative/unknown in AP vs. 0/54/2 in JP) (p < 0.01).　

Discussion: This analysis revealed significant differences in macroscopic types, tumor grade and background mucosa between AP and JP with early-stage EGJ adenocarcinomas. These findings suggest distinct pathways of carcinogenesis.

Disclosures:
Keiko Yamamoto indicated no relevant financial relationships.
Yukihiro Nakanishi indicated no relevant financial relationships.
Hiroaki Takahashi indicated no relevant financial relationships.
Emi Takakuwa indicated no relevant financial relationships.
Naoya Sakamoto indicated no relevant financial relationships.
Schaffer Mok: Amgen – Consultant. Steris – Consultant.
Jose Pimiento indicated no relevant financial relationships.
Gregory Lauwers indicated no relevant financial relationships.

Keiko Yamamoto, MD, PhD¹, Yukihiro Nakanishi, MD, PhD¹, Hiroaki Takahashi, MD, PhD², Emi Takakuwa, MD, PhD³, Naoya Sakamoto, MD, PhD³, Schaffer Mok, MD¹, Jose Pimiento, MD¹, Gregory Lauwers, MD¹. P0628 - The Differences in the Clinicopathological Features of Early-Stage Adenocarcinomas of the Esophagogastric Junction Between the United States and Japan, ACG 2025 Annual Scientific Meeting Abstracts. Phoenix, AZ: American College of Gastroenterology.