The study focuses on patients with synchronous liver metastasis from pancreatic adenocarcinoma that underwent both pancreatic and liver resection. The control group is made up of patients with resectable or borderline resectable pancreatic adenocarcinoma and synchronous liver metastasis that were excluded from surgery. Short and long-term outcomes will be compared to evaluate the safety and efficacy of simultaneous liver and pancreatic resection.

1. Summary:

   The study focuses on patients with synchronous liver metastasis from pancreatic adenocarcinoma that underwent both pancreatic and liver resection. The control group is made up of patients with resectable or borderline resectable pancreatic adenocarcinoma and synchronous liver metastasis that were excluded from surgery. Short and long-term outcomes will be compared to evaluate the safety and efficacy of simultaneous liver and pancreatic resection.

2. Introduction 2.1 Background and rationale The most common pathological pattern of pancreatic tumor is pancreatic ductal adenocarcinoma (PDAC), which accounts for approximately 90% of all cases. For digestive tract tumors such as colorectal, gastric, and pancreatic tumors, distant metastases often represent the last stage of the disease evolvement, and liver is a frequent disseminate site for metastatic tumor. Among them, only hepatic resection for metastatic disease has gained general acceptance as a potentially curative option in patients with colorectal cancer. The role of surgery for metastases from neuroendocrine tumors on long-term outcome is also well-documented. Recently, Markar et al. reported that surgical resection of hepatic metastases from gastric adenocarcinoma was associated with a significantly improved overall survival (p < 0.001). Moreover, they confirmed the additional survival benefit of solitary compared with multiple hepatic metastases (odds ratio = 0.31; p = 0.011). Liver resection showed longer survival rates also for pancreatic neuroendocrine tumor (PNET) patients.

   However, historical results regarding hepatic resection for PDAC were in conflicts and remained controversial. Furthermore, rare systematic review or meta-analysis was ever reported focusing on PDAC as a separate group. A recent meta-analysis reported that overall survival of PDAC patients can benefit from hepatic resection to some extent. It has been also recently showed that that surgical resection of pancreatic cancer with synchronous liver oligometastases is safe, and it can be associated with improved survival, providing a careful selection of patients after primary chemotherapy. Since a randomized controlled trial may be ethically questionable, a multicenter international retrospective study may clarify the role of liver resection in this cohort of patients.

   2.2 Objectives

   The primary aim is to examine recurrence free survival (RFS) and overall survival (OS) following surgical resection of synchronous hepatic metastases from PDAC, and to study the role of tumor burden and chemotherapy regimen on survival.

3. Methods:

3.1 Study design Patients underwent liver resection for synchronous metastases from pancreatic adenocarcinoma, single or multiple metastasis, will be included in the study, without any time interval limitation.

Clinical features, operative data and chemotherapy regimens will be analyzed. A control group of non-surgical patients will be included in the study for a propensity score match.

3.2 Setting

• No time interval limitation for recruitment
• No volume-based restriction for center eligibility 3.3 Participants Patients of age >18, underwent surgery for pancreatic adenocarcinoma (duodenopancreatectomy, distal pancreatectomy, total pancreatectomy) and liver resection (major or minor) for synchronous metastasis, that received neoadjuvant and/or adjuvant chemotherapy. The control group is made up of patients age >18 with resectable or borderline resectable pancreatic adenocarcinoma and synchronous liver metastasis that didn't underwent surgery.

Inclusion Criteria:

• Patients of age >18, underwent surgery for pancreatic adenocarcinoma (duodenopancreatectomy, distal pancreatectomy, total pancreatectomy) and liver resection (major or minor) for synchronous metastasis, that received neoadjuvant and/or adjuvant chemotherapy.
• The control group is made up of patients age >18 with resectable or borderline resectable pancreatic adenocarcinoma and synchronous liver metastasis that didn't underwent surgery.

Patients underwent liver resection for synchronous metastases from pancreatic adenocarcinoma, single or multiple metastasis, will be included in the study, without any time interval limitation. Clinical features, operative data and chemotherapy regimens will be analyzed. A control group of non-surgical patients will be included in the study for a propensity score match. Setting

• No time interval limitation for recruitment
• No volume-based restriction for center eligibility