The purpose of this study is to investigate the safety and efficacy of HFRT plus neoadjuvant ICT in locally advanced resectable GEJA.
Histologically and/or cytologically confirmed diagnosis of locally advanced adenocarcinoma of the gastroesophageal junction (GEJ) (Siewert types I-III), defined as cT3-4, any N, M0 or cT2 N+, M0 according to the 8th edition of the AJCC staging system.
Determined as resectable locally advanced disease after multidisciplinary team (MDT) evaluation.
Age ≥18 years, regardless of sex.
Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.
Confirmed dMMR or MSI-H by immunohistochemistry or genetic testing.
Evidence of peritoneal or visceral metastasis (based on thoracoabdominal CT, bone scan, or MRI if bone metastasis is suspected).
Other malignancies within the past 5 years, except cured basal cell or squamous cell carcinoma of the skin, or carcinoma in situ of the cervix.
Known allergy or hypersensitivity to any study drugs or their excipients; contraindications to study drugs.