MESOPANC-01 Study: The Mesopancreas and the Ductal Adenocarcinoma of the Pancreatic Head: From Preoperative Imaging to Histopathological and Surgical Outcome

For patients with a ductal adenocarcinoma of the pancreatic head (PDAC) pathological evaluation of the pancreatoduodenectomy specimen has endured a redefined process. After the Introduction of the pathological circumferential resection margin, residual cancer (R1 resection) was most often found in the dorsal and medial resection margins. Yet only the medial resection margin is preoperatively evaluated by staging and utilized during assessment of resectability. The dorsal resection margin which resides residual cancer (R1 resection) at a similar rate compared to the medial resection margin, is not considered during preoperative assessment for resectability. After the inclusion of the pathological LEEPP protocol true R0 resection rates have dropped to ~30%.

Next to the poor systemic tumor control and thus early detected relapse in PDAC patients, local recurrence is evenly at risk and remains an ungoing dilemma. Revised pathological outcome by the implemented LEEPP protocol explains the poor local tumor control.

The aim of this study is to interdisciplinary approach the circumferential infiltration status of the PDAC concentrating foremost on the dorsal resection margin by including anatomic and embryologic derived perspectives.

These perspectives have already been implemented by complete mesocolic and total mesorectal excision. The mesocolon of the ascending colon is embedded dorsally by fascia sheets, resulted by the embryologic fusion process, and the anatomic landmark of this fascia sheet has gained significant clinical relevance for radical surgical resection (Toldt fascia for total mesocolic excision). While surgical perspectives for the colorectal system have included the anatomic and embryologic nature of the colon and rectum, these landmarks and the idea of ''compartment anatomy'' are not implemented during pancreatoduodenectomy.

It seems rational to suggest that redefined surgical standards for colorectal cancer patients with implemented fascial sheets as anatomic landmarks could be translated to the pancreas as well. Similar to the ascending colon; the pancreas remains secondary retroperitoneal. The Treitz fascia is a cranio-medial extension of the toldts fascia, which again is an anatomic landmark for total mesocolic excision. The superior mesenteric artery serves as an anchor point for the embryologic rotation process of the pancreas until it remains secondary retroperitoneal. From an anatomic and embryologic point of view, there should not be any doubt for the existence of a mesopancreas.