Ablative Carbon Ion Radiotherapy With Pencil Beam Scanning for Locally Advanced Unresectable Pancreatic Cancer

Inclusion Criteria: 1. Have the ability to sign the written informed consent; 2. Ductal adenocarcinoma of the pancreas confirmed by histopathology or cytopathology; 3. Distant metastasis was excluded by imaging assessment (PET-CT, cranial MRI), and was defined as locally advanced unresectable according to NCCN Guidelines Version 2022.1, that is, T4N0-2M0, Stage III (AJCC/UICC Version 8); 4. The maximum diameter of pancreatic primary lesion and positive lymph node ≤7cm; 5. Pancreas primary lesion or positive lymph node did not invade digestive tract (stomach, duodenum and small intestine); 6. Eastern Cooperative Oncology Group (ECOG) performance score 0-1; 7. Adequate bone marrow function (neutrophil count ≥1.5×109/L, platelet count ≥100×109/L, hemoglobin ≥10.0g/dL); 8. Adequate liver function (total bilirubin \<1.5 times the upper limit of normal value, aminotransferase \<2.5 times the upper limit of normal value); 9. Adequate renal function (serum creatinine \<2mg/dL, or creatinine clearance \>50mL/min). Exclusion Criteria: 1. Multiple primary pancreatic lesions (\>1); 2. Tumor invaded the adjacent digestive tract; 3. Radiation therapy history; 4. Other local treatments history for pancreatic cancer, such as HIFU and irreversible electroporation; 5. The irradiation dose of organs at risk cannot reach the dose constraint; 6. Other malignant tumors history; 7. Inability to understand the purpose of treatment or unwillingness/inability to sign informed consent.