Pancreatic cancer is a highly fatal malignant tumor. Simple surgical operations can no longer meet the treatment needs of pancreatic cancer patients. Postoperative adjuvant chemotherapy has a significant effect, which can effectively prevent or delay tumor recurrence and prolong the overall survival period of pancreatic cancer patients. Based on this, many guidelines both at home and abroad actively recommend that pancreatic cancer patients receive adjuvant chemotherapy after surgery (if there are no contraindications). Radiotherapy is one of the most commonly used local treatment methods. It can be used as a neoadjuvant or adjuvant therapy to increase the tumor resection rate or reduce the recurrence rate, or as a treatment approach for locally unresectable pancreatic cancer to improve local control. After complete gross resection of pancreatic cancer, the role of radioadjuvant therapy has always been controversial, and its indications for use remain unclear. However, recent clinical studies using modern radiotherapy equipment and techniques have shown that an increasing amount of data indicates that radiotherapy can benefit in the treatment of neoadjuvant, adjuvant and locally advanced pancreatic cancer. Evidence supporting adjuvant radiotherapy after pancreatectomy remains scarce. Therefore, whether screening high-risk factor populations for adjuvant radiotherapy may improve the prognosis of pancreatic cancer is an important research.

Inclusion Criteria:

• Understand and voluntarily participate in this study and sign the informed consent form
• Age ≥18 years old and ≤75 years old, male and female.
• Confirmed as pancreatic ductal adenocarcinoma by histopathology or cytology, with no evidence of distant metastasis confirmed by imaging.
• The preoperative neoadjuvant chemotherapy regimen is not limited and should not exceed 4 cycles. After the operation was completed, at least one postoperative high-risk factor was present :R1/R2 resection. Regional LN transfer Neurovascular invasion The pathology is poorly differentiated. Tumor height >4cm;
• No disease progression was evaluated by CT or MRI after the operation.
• The subjects have sufficient organ and bone marrow functions: absolute neutrophil count ≥1.5×109, platelet count ≥80×109, hemoglobin ≥90g/L; Total bilirubin levels ≤1.5 times the upper limit of normal (ULN), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels ≤2.5 times ULN. Serum creatinine ≤1.5 times ULN or creatinine clearance ≥60 ml/min(Cockcroft-Gault formula);
• ECOG PS score 0-1;
• The expected postoperative survival period is ≥3 months;
• Women of childbearing age who are not pregnant and have no pregnancy plans. Patients of childbearing age and their spouses are willing to take contraceptive measures that have been medically approved.

Exclusion Criteria:

• Had received radiotherapy, palliative chemotherapy or other targeted or immunotherapy for anti-tumor treatment before pancreatic tumor resection;
• Suffering from severe underlying diseases, including but not limited to: active infections that require systemic medication treatment; Uncontrolled diabetes and hypertension; Negligent compensatory heart failure (NYHA grades III and IV), unstable angina, and acute myocardial infarction occurred within 3 months before enrollment. Malignant peritoneal effusion or pleural effusion; Severe portal hypertension or imaging manifestations of cavernous changes in the portal vein; Gastric outlet obstruction, respiratory insufficiency (requiring oxygen inhalation) and severe lung diseases; Central nervous system diseases, mental disorders;
• There is a history of other malignant tumors (cured basal cell carcinoma of the skin and cervical carcinoma in situ)
• There is bleeding or coagulation disorder;
• Postoperative complications such as bleeding, pancreatic fistula, gastric emptying disorder, abdominal infection, and biliary fistula occur, which prevent the patient from receiving adjuvant treatment within 12 weeks after the operation.
• Those who are allergic to the drugs or their components used in this plan;
• Known to be infected with HIV or syphilis, or currently in the active stage of hepatitis (hepatitis B, hepatitis C);
• Female subjects who are pregnant or breastfeeding, or plan to become pregnant during the study period, or female spouses of male subjects;
• The subjects had poor compliance and were unable to follow the various procedures, restrictions or requirements of the study, etc.
• There are other reasons that the researcher deems unsuitable for participation in this study.