Comprehensive histological evaluation with clinical analysis of venous invasion in pancreatic ductal adenocarcinoma: From histology to clinical implications.

OBJECTIVES: Venous invasion is a poor prognostic factor for pancreatic ductal adenocarcinoma (PDAC). However, our understanding of various features of venous invasion is limited. Our aim is to comprehensively evaluate various histopathologic features of venous invasion, including status, type (lymphatic or venous), number of invasion foci, and histologic pattern (pancreatic intraepithelial neoplasia [PanIN]-like, conventional) in PDACs. METHODS: Various features of venous invasion, including status, number of invasion foci, histologic patterns [pancreatic intraepithelial neoplasia (PanIN)-like, conventional], and size of involved vessels in 471 surgically resected PDACs were evaluated with all available hematoxylin and eosin (H&E)-stained slides. RESULTS: Venous invasion was observed in 319 cases (67.7%) and was more frequently associated with increased tumor size, extrapancreatic extension, resection margin involvement, diffuse tumor distribution, lymph node metastasis, and perineural invasion (all Ps < .05). High frequency (≥3 foci) of venous invasion was associated with shorter overall survival both in the entire group and in the early stage subgroup (stage I; all Ps < .05). Multivariate analysis indicated that a high frequency (≥3 foci) of venous invasion, large tumor size (>4 cm), higher histologic grade, and lymph node metastasis, were independent prognostic factors of worse overall survival (all Ps < .05). CONCLUSION: Precise evaluation of venous invasion status, including foci number of invasion, can provide additional prognostic information for patients undergoing surgical resection of PDAC, especially for those with early disease stage.

Lymph node size and its association with nodal metastasis in ductal adenocarcinoma of the pancreas.

BACKGROUND: Although lymph node metastasis is a poor prognostic factor in patients with pancreatic ductal adenocarcinoma (PDAC), our understanding of lymph node size in association with PDAC is limited. Increased nodal size in preoperative imaging has been used to detect node metastasis. We evaluated whether lymph node size can be used as a surrogate preoperative marker of lymph node metastasis. METHODS: We assessed nodal size and compared it to the nodal metastatic status of 200 patients with surgically resected PDAC. The size of all lymph nodes and metastatic nodal foci were measured along the long and short axis, and the relationships between nodal size and metastatic status were compared at six cutoff points. RESULTS: A total of 4,525 lymph nodes were examined, 9.1% of which were metastatic. The mean size of the metastatic nodes (long axis, 6.9±5.0 mm; short axis, 4.3±3.1 mm) was significantly larger than that of the non-metastatic nodes (long axis, 5.0±4.0 mm; short axis, 3.0±2.0 mm; all p<.001). Using a 10 mm cutoff, the sensitivity, specificity, positive predictive value, overall accuracy, and area under curve was 24.8%, 88.0%, 17.1%, 82.3%, and 0.60 for the long axis and 7.0%, 99.0%, 40.3%, 90.6%, and 0.61 for the short axis, respectively. CONCLUSIONS: The metastatic nodes are larger than the non-metastatic nodes in PDAC patients. However, the difference in nodal size was too small to be identified with preoperative imaging. The performance of preoperative radiologic imaging to predict lymph nodal metastasis was not good. Therefore, nodal size cannot be used a surrogate preoperative marker of lymph node metastasis.