Perioperative Factors Linked to Increased Risk for Thrombosis During Pancreatectomy With Venous Resection: the Influence of Technical Factors and Perioperative Antithrombotic Prophylaxis.

Pancreatic surgery is the only treatment in the multimodality approach to pancreatic cancer sine qua non long-term survival cannot be achieved. Pancreatectomy with vein resection (PVR) of the portal vein and the superior mesenteric vein (PV/SMV) to address tumors with venous infiltration has become standard of care in pancreatic surgery for the past 20 years. Larger series and meta-analyses show that long-term survival beyond the 5-year threshold can be achieved with PVR, but with somewhat inferior survivor compared to standard pancreatic resections without venous resection. That is most likely due to the fact that tumors necessitating PVR are generally larger, less differentiated, and more likely to express unfavourable features such as perineural infiltration.

Recent publications point out that PVR can be performed in pancreatic centers around the world with comparable morbidity and mortality, irrespective of the countries' income status. Also, benchmark outcomes for PVR in low-risk patients have been established, defining that the accepted risk for venous thrombosis should be lower than 14% at discharge. Despite that, a questionnaire among expert surgeons reveals that even if PVR is considered a standard procedure, surgeons are still concerned about significant morbidity. Also, the perception as to what proportion of patients require venous resection, how it should be performed and what anti-thrombotic prophylaxis should be given varies widely. The reported morbidity and thrombosis rates after different types of venous resections and reconstructions vary from under 2 to over 25%. There is no consensus as to which type of venous reconstruction is associated with most favourable short- and long-term outcomes, what specific surgical manoeuvres and graft materials decrease the overall complication and the vein-resection specific complications rates and what anti-thrombotic prophylaxis is safest (associated with lowest thrombosis rates and bleeding complications). Although some studies suggest that grafts are associated with higher thrombosis rates, there is no profound investigation as to how to avoid the use of grafts or, if necessary, what grafts are associated with least thrombotic risks while not causing increased patient morbidity.

The purpose of this study is to evaluate different technical manoeuvres, anti-thrombotic prophylaxis strategies and organisational features in a large cohort of patients undergoing PVR in median and large-volume centers in order to assess which factors contribute to vein resection-related specific morbidity.

The study design is an international multi-center observational cohort study, with retrospective and prospective part, including patients who underwent pancreatic surgery with PV/SMV resection from 2018 to June 30 th 2025 and prospectively 18 months ahead. Perioperative factors, related to technical decisions, perioperative resuscitation, institutional organisational specificities, and anti-thrombotic prophylaxis, associated with increased risk for early (30-day), intermediate 30 days-6 months and late venous thrombosis (>6months) will be analysed. The thrombosis rate among the four types of venous reconstructions will be compared while adjusting for the length of the resected vein segment. Median and high-volume pancreatic centers (>20 pancreatic resected /year).

The inclusion criteria are: patients undergoing radical pancreatic resection with simultaneous PV/SMV resection, irrespective of final pathology operated between January 1 st 2018 - June 30 th, 2025 (retrospectively) or from July 1 st 2025-December 30 th, 2026 (prospectively). Patients with distant metastases (M1), <18 years of age or undergoing R2 resection will be excluded.

The study intends to include over 1000 patients. The main objective is to assess the perioperative factors (technical, organisational, anti-thrombotic treatment) associated with increased risk for early (30 days), intermediate (>30 days-6 months) and late (>6 months) venous thrombosis.