The Usefulness of Neoadjuvant Chemotherapy for Siewert Type Ii Egj Adenocarcinoma

Background In Japan, neoadjuvant chemotherapy (NAC) is the standard treatment for clinical stage II/III thoracic esophageal cancer; however, its role in clinical stage II/III adenocarcinoma of the esophagogastric junction (EGJ) remains unclear. The 5th edition of the Japanese Esophageal Cancer Treatment Guidelines does not provide a clear recommendation for this subgroup. Methods We retrospectively reviewed 85 patients with Siewert type II EGJ adenocarcinoma who underwent surgery at our institution between January 2016 and April 2025. Among them, 54 patients with clinical stage II/III disease were analyzed to compare outcomes based on disease stage and use of NAC. Results Of the 54 patients, 14 received NAC. The NAC regimens included SOX (n = 13) and FLOT (n = 1). Patients were categorized into three groups: clinical stage II without NAC (A, n = 16), clinical stage III with upfront surgery (B, n = 24), and clinical stage III with NAC (C, n = 14). The 3-year OS rates were 76.9% in A, 72.3% in B, and 90.9% in C. The corresponding 5-year OS rates were 51.3%, 62.0%, and 51.9%, respectively. Although C showed a trend toward better 3-year OS, no statistically significant differences were observed among the groups. Conclusion NAC with SOX for Siewert type II EGJ adenocarcinoma did not demonstrate clear clinical benefit, highlighting the need for more effective regimens. Results from the ongoing randomized phase II/III JCOG trial evaluating DOS and FLOT are eagerly awaited.