The goal of this clinical trial is to compare the overall survival of thermal ablation combined with chemotherapy and chemotherapy alone in the patients with liver oligometastasis after pancreatic ductal adenocarcinoma (PDAC) surgery.

The main question it aims to answer is: whether thermal ablation combined with chemotherapy can effectively prolong the overall survival in the patients with liver oligometastasis after pancreatic ductal adenocarcinoma (PDAC) surgery.

The participants in the treatment group will receive systemic chemotherapy combined with liver thermal ablation, while the participants in the control group will receive chemotherapy alone. All participants will be followed up to evaluate the overall survival after treatment.

How to improve the overall survival in the patients with liver oligometastasis after pancreatic ductal adenocarcinoma (PDAC) surgery is still a huge challenge in clinic. Chemotherapy is still the first-line treatment for patients with liver oligometastasis after PDAC resection. On the basis of chemotherapy, the clinical benefits of removing hepatic oligometastasis by thermal ablation are still unclear. In this study, we will recruit patients with liver oligometastasis after PDAC surgery to explore the effect of thermal ablation combined with chemotherapy on the overall survival of patients.

Inclusion Criteria:

• (1) Age ≥ 18; (2) pancreatic ductal adenocarcinoma was confirmed by pathology; (3) The patient's liver function was Child Pugh A or B ; (4) Karnofsky score ≥ 80; (5) There is a safe puncture path under the guidance of ultrasound for liver oligometastatic tumor; (6) Single diameter of liver oligometastatic tumor ≤ 5 cm, or ≤ 3 liver oligometastatic tumors, each diameter ≤ 3 cm; (7) Platelet count>40000/mm3; (8) Thrombin time ratio>40%; (9) Sign the Informed Consent of Clinical Trial.

Exclusion Criteria:

• (1) Refuse to receive chemotherapy or thermal ablation; (2) >3 liver metastases or extrahepatic metastases (such as peritoneum, lung, bone or brain); (3) Single diameter of liver oligometastatic tumor>5 cm; (4) The patient has ascites, portal vein thrombosis, or bile duct dilatation or stenosis; (5) Presence of another malignant tumors; (6) Prior anti-tumor treatment (including radiotherapy, chemotherapy and thermal ablation); (7) Presence of central nervous system abnormalities, mental diseases, unstable angina, congestive heart failure, serious arrhythmia or other serious diseases; (8) Use of anticoagulants maintenance treatment.