This study aims to conduct a large-scale prospective clinical trial to evaluate the efficacy and safety of capecitabine monotherapy as maintenance treatment following standard adjuvant chemotherapy (gemcitabine plus capecitabine) in patients with resectable pancreatic cancer, and to analyze whether ctDNA-MRD testing can guide the selection of postoperative maintenance therapy.

Inclusion Criteria:

• Age ≥18 years, male or female
• Histologically or cytologically confirmed primary diagnosis of pancreatic ductal adenocarcinoma (PDAC)
• No evidence of distant metastasis (M0)
• Underwent R0 radical resection within 3 months prior to enrollment
• ECOG performance status of 0-1
• Life expectancy ≥3 months
• Patient or legal guardian is able to understand the study requirements and willing to provide written informed consent

Exclusion Criteria:

• Prior history of radiotherapy, chemotherapy or surgical treatment for pancreatic cancer
• Concurrent severe organ dysfunction or hematologic disorders
• Tumor involvement of celiac axis or superior mesenteric artery, locally advanced disease, or presence of distant metastases
• Poor general condition deemed unable to tolerate chemotherapy
• History of other malignancies within past 5 years (except adequately treated carcinoma in situ of cervix or basal cell carcinoma of skin)
• Any severe or uncontrolled systemic disease that may affect risk/benefit assessment, including but not limited to: uncontrolled hypertension, active hepatitis B or C infection, HIV infection
• Patient or guardian unable to comprehend study objectives and requirements
• Any other condition that in the investigator's judgment would make the patient unsuitable for study participation

Pancreatic caner patients with R0 surgery