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.