Phase II Study of Conversion Therapy with Surgery and Para-Aortic Radiotherapy for Gastric Adenocarcinoma with Isolated Retroperitoneal Lymph Node Metastases

What this Trial Is About

Researchers are evaluating a new treatment approach for patients with gastric adenocarcinoma who have isolated metastases to the para-aortic station 16 lymph nodes without spread to the peritoneum, other distant organs, or non-regional lymph nodes. This is a randomized, controlled phase II study aiming to see if adding locoregional treatments like surgery and radiotherapy to systemic therapy improves long-term outcomes compared to standard chemotherapy alone. The study also explores biomarkers and immune environment features to better understand treatment responses. Participants are assigned to one of two groups based on their PD-L1 combined positive score CPS. In the experimental group, patients with CPS 651 receive 3 cycles of SOX chemotherapy plus a PD-1 inhibitor, then undergo radical gastrectomy followed by 5 cycles of adjuvant SOX chemotherapy and intensity-modulated radiotherapy IMRT to the para-aortic lymph nodes with concurrent oral capecitabine or S-1 as radiosensitizers. Maintenance PD-1 inhibitor therapy continues for up to one year in these patients. Those with CPS less than 1 receive SOX alone followed by the same surgery, chemotherapy, and radiotherapy schedule. The control group receives standard chemotherapy with CAPEOX or SOX, with or without immunotherapy, but no surgery or radiotherapy. During the study, participants provide tumor tissue, blood, and fecal samples for biomarker studies. Researchers monitor treatment effects through progression-free survival at two years as the primary outcome, along with overall survival, response rates, disease control, and safety over approximately three years. Follow-up lasts for 24 months after enrollment, allowing careful assessment of long-term outcomes and adverse effects. A total of 54 patients will enroll with a planned accrual period of 18 months.

Conversion Therapy Plus Surgery and Radiotherapy for Retroperitoneal Nodal Metastases in Gastric Cancer