This study is a multi-center phase 3 trial to evaluate a treatment strategy for selecting patients who can benefit from the synchronous resection of primary pancreatic cancer and liver oligometastasis after induction chemotherapy. Half of participants who meet the entry criterion will receive surgical intervention, while the other half will continue to receive standard chemotherapy.

Note: This study has two steps. In the first step, patients who meet the criteria for candidates will receive standard first-line chemotherapy for pancreatic cancer. Response Evaluation Criteria in Solid Tumors (RECIST) criteria was employed to measure tumor's response to chemotherapy every two cycles. Until some of them meet the criteria for intervention, they will be randomized and receive relevant interventions.

Inclusion Criteria for candidates:

1. Voluntary participation
2. 18-75 years old
3. Eastern Cooperative Oncology Group (ECOG) 0-1
4. Stage IV pancreatic cancer with no more than 3 liver metastases
5. Histologically confirmed diagnosis of pancreatic cancer
6. No contraindication of chemotherapy

Exclusion Criteria for candidates:

1. Not want to receive chemotherapy or potential operation.
2. Metastases at other sites except for liver
3. With other malignancies
4. Receive chemotherapy, radiotherapy, and interventional therapy before
5. Contraindication of potential operation

Inclusion Criteria for intervention:

1. Primary tumor and liver metastatic sites are both resectable.
2. No new metastatic sites were observed
3. Abnormal serum tumor maker levels decreased by more than 50% after chemotherapy. In the serum tumor makers, carbohydrate antigen 19-9 (CA19-9) was always the first choice for evaluation and it should be below 500U/L after treatment. However, when the baseline CA19-9 was within the normal range, carbohydrate antigen 125 (CA125) and carcinoembryonic antigen (CEA) were the alternative candidate indicators.

Exclusion Criteria for intervention:

1. Contraindication of operation