A histopathological study of artery wall involvement in pancreatic cancer surgery.

PURPOSE: This study aims to study the depth of artery wall tumour invasion in patients undergoing surgery for pancreatic ductal adenocarcinoma. METHODS: Specimens from 47 pancreatic cancer patients with major arterial (splenic, SA; celiac, CA; common hepatic, CHA) invasion were examined: 45 left (distal) pancreatectomies, including 11 celiac artery resections, and two total pancreatectomies. Dissection of tumour-invaded arteries in 25 fresh specimens was attempted ex vivo using the sub-adventitial dissection technique (SDT). Tumour invasion of 66 arteries was graded using the tumour-free distance (TFD) from the external elastic lamina (EEL): 0 = no arterial invasion; I = TFD ≥ 1 mm; II = TFD < 1 mm; and grade III = EEL invasion. RESULTS: AJCC TNM staging was IA = 1 (2%), IB = 4 (9%), IIA = 5 (11%), IIB = 17(36%) and III = 20 (43%). Grade III tumour invasion was found in 17/47(36%) SAs, in 5/11 (45%) CAs and in 1/8 (13%) CHAs (p = 0.318). Attempted ex vivo SDT undertaken in 33 arteries from 25 specimens was complete in 16 and incomplete in 17 arteries. The median (IQR) TFD was 0.97 (0.11-2.54) mm in dissected and 0.14 (0.10, 0.14) mm in non-dissected SAs (p = 0.034). EEL tumour invasion occurred in 0/12 (0%) dissected compared to 7/13 (54%) non-dissected SAs (p = 0.005). Grades 0, I, II and III invasion were found in four (33%), two (17%) and six (50%), respectively, of 12 dissected SAs and grades II and III in six 6 (46%) and seven (54%), respectively, of 13 non-dissected SAs (p = 0.002). CONCLUSIONS: The grading system described may form the basis for classification to further develop arterial dissection techniques for pancreatic cancer.