Pathology and biology of pancreatic ductal adenocarcinoma

Ductal adenocarcinoma of the pancreas is a highly aggressive tumor with early local spread beyond the pancreas, predominantly to the retroperitoneum, but also with invasion of adjacent great vessels and adjacent organs.

Anterior extension may lead to perforation of the visceral peritoneum and spread within the peritoneal cavity. Cytology in peritoneal lavage can be positive before any peritoneal metastasis is seen. Invasion of lymphatics and veins as well as perineural invasion are common. The lymph drainage of the pancreas is multidirectional to superior, inferior, anterior, posterior and left lymph nodes. In node-negative cases, isolated tumor cells in the sinus of regional lymph nodes may be found by immunocytochemistry; such findings must be distinguished from micrometastasis. The same applies to isolated tumor cells in bone marrow.

The independent prognostic significance of isolated tumor cells in the regional lymph nodes and in the bone marrow remains to be proven. For classification of anatomic extent the new, fifth edition ( 1997) of the UICC TNM classification should be used. The complex Japanese classification cannot be directly compared with the UICC system.

Tumor size and histologic grade influence the extent of spread. Anatomic extent and histologic grade are the strongest predictors of outcome.