Locally advanced gastroesophageal junction cancer with pathological complete response to neoadjuvant therapy: a case report and literature review.

Most gastric cancer and gastroesophageal junction carcinoma (GEJ) patients are already in the advanced stage at the time of diagnosis. Thus, the probability of radical gastrectomy is low, and surgical treatment alone has a poor prognosis due to the high recurrence rate. In order to reduce the recurrence and distant metastasis after surgery, there have been many attempts made to improve the perioperative treatment of advanced localized gastric cancer, but no uniform criteria exist. Over recent years, immunotherapy has revolutionized cancer treatment, and immune checkpoint inhibitors (ICIs) have shown excellent efficacy across various types of tumors, becoming a potential treatment after surgery, chemotherapy, radiotherapy, and targeted therapy. However, the efficacy of single-agent ICIs for gastric cancer is still unsatisfactory. As comprehensive, chemotherapy-based treatment has become the standard care for locally advanced gastric cancer, exploring combination treatment with immune checkpoint inhibitors (ICIs) may be valuable to improving survival outcomes. Here, we report a 66-year-old male with dysphagia diagnosed with GEJ and was defined as clinical stage (cT4N2M0) and Siewert type II, characterized as mismatch repair proficient (pMMR) and programmed cell death ligand-1 (PD-L1) negative; surprisingly, with anti-PD-1 antibody plus SOX (S-1: a combination of tegafur, gimeracil, and oteracil+ oxaliplatin) as perioperative therapy, the patient achieved pathological complete remission (pCR), which indicates that the addition of ICIs to chemotherapy as a perioperative comprehensive treatment might provide a promising strategy option for GEJ. In addition, we review the current status of perioperative comprehensive treatment, in hope that this may provide some reference value for clinical decision-making.