Multicolour Versus Monocolour Specimens Inking After Pancreaticoduodenectomy for Periampullary Cancer

This study was a single-centre, prospective, controlled, open, parallel group, randomised clinical trial, conducted in the tertiary referral University Centre of S.Orsola-Malpighi Hospital, Bologna, Italy, from June 2012 to January 2016, which enrolled patients affected by periampullary cancer who underwent pancreaticoduodenectomy (PD). All patients with suspected periampullary cancer were enrolled in the study, but only patients who underwent pancreaticoduodenectomy were randomised and allocated to a multicolour inking specimen (arm A, experimental) or a monocolour inking (arm B, control) after specimen was taken out from the operative field. The analysis regarded only the specimens of the patients who underwent PD in which the final pathologic report showed a diagnosis of invasive periampullary cancer (pancreatic, ampullary and distal bile duct).

After performing the pancreaticoduodenectomies, the surgeon intraoperatively inked the surfaces/margins of the specimen with different colours. In the multicolour arm, the surfaces/margins inked were the following: Anterior surface of the pancreas (yellow); Posterior surface of the pancreas (orange); Superior mesenteric/portal vein groove (blu); Superior mesenteric artery margin (retroperitoneal margin) (red); Transection margin of the bile duct (green).The trans-section pancreatic and gastric margins were not inked.

In the monocolour arm, only the superior mesenteric artery margin and the pancreatic margin were intraoperatively indicated by the surgeon in the specimen: a single stitch to identify the transection pancreatic margin and a continuous suture to identify the superior mesenteric artery margin. Monochromatic inking of the superior mesenteric artery margin was subsequently carried out by the pathologist. In both arms of treatment, the macroscopic evaluation and slicing of the surgical specimen followed the Leeds Pathology Protocol (LEEPP), and seven margins, which included the anterior, posterior, superior mesenteric /portal vein groove, superior mesenteric artery, bile duct, pancreatic neck and stomach margins, were examined. The primary endpoint was to evaluate the overall R1 resection rate and its difference between multicolour (arm A) and monocolour (arm B) inking of the specimen. The secondary endpoints were to evaluate the R1 resection rate in each margin: anterior and posterior surfaces of the pancreatic head; superior mesenteric/portal vein groove; superior mesenteric artery margin; transection pancreatic and bile duct margins, and its difference between the two arms compared. Finally, the impact of the margin status on survival was considered for each margin and type of periampullary tumours.

Calculation of the sample size was based on the literature assumption that the overall incidence rate expected of R1 ranged from 10 to 76% while it increased to 81-85% when a standardised pathological technique and margination with multicolour inking, as described in arm A, was performed. To detect a difference in R1 rate between these values with a 5% alpha-error and a 80% beta-error at a two-sided 0.05 significance level, a sample size of 18 patients was required for each group. In relation to the fact that the patients were often randomised without a preoperative biopsy, and that following current literature the 5-13% of the presumed malignancies were benign, it was decided to randomise 25 patients in order to avoid a sample size smaller than expected. The sample size calculation was carried out using PS Power and Sample Size Calculation software (Department of Biostatistics; Vanderbilt University; Nashville, TN, USA).