Most oncological pancreas resections must consider the mesopancreas.

Background: In preoperative staging for patients with a ductal adenocarcinoma of the pancreatic head (PDAC), resectability is anatomically characterized by the possible clearance of the medial vascular grove. Borderline resectable PDAC patients who retain an increased risk of infiltration to the portomesenteric system and/or arterial vasculate are candidates for neoadjuvant therapy. However, redefined pathological analysis revealed the dorsal resection margin to be similar at risk for R1 resection. Mesopancreatic excision (MPE) aims to secure the integrity of the dorsal and ventral resection margins. The existence of the mesopancreas (MP) is inevitable, since the pancreas is of a secondary retroperitoneal nature and the dorsal as well as ventral fascial coverings define the peripancreatic compartment anatomy. It remains unknown if the MP area is only infiltrated in high-risk PDAC patients or if MPE during pancreatoduodenectomy should be employed for localized PDAC patients as well.

Methods: Patients who underwent upfront pancreatoduodenectomy were included. CRM evaluation and analysis of the MP was standardized in all patients. Patients were sub-grouped by the infiltration status of the vascular groove (localized disease: LOC). In LOC patients there was evidently no cancerous infiltration into the medial vascular groove (true + primary resectable).

Results: Two hundred eighty-four consecutive patients who underwent pancreatoduodenectomy were included (169 LOC patients). In LOC patients the MP infiltration rate remained high but was significantly lower when compared to advanced PDAC patients (MP + 69.2% vs. 83.5%, p = 0.005). In LOC patients, CRM resection status of the dorsal resection status remained significantly affected by the MP infiltration status (R0CRM- 80.5% vs. 62.8%, p = 0.019).

Conclusion: These important findings clearly show underestimated tumor extensions into the mesopancreas even in localized, primary resectable PDAC patients who are currently amenable for upfront resection. Synergistically to total mesorectal or mesocolic excision, which is applied to all stages of colorectal disease, MPE is justified in primary resectable patients as well. Therefore, MPE should be employed in all PDAC patients. Since the infiltration status of the mesopancreas was a significant factor for incomplete resection in primary resectable PDAC patients, neoadjuvant treatment options for must be discussed.