Aggressive venous invasion in the area of carcinoma correlates with liver metastasis as an index of metastasis for invasive ductal carcinoma of the pancreas

Abstract Background Invasive ductal carcinoma of the pancreas (IDCP) predominantly causes death through liver metastasis (LM) and peritoneal dissemination with local recurrence. However, whether its venous invasion is from the enlarged carcinoma accompanied by tumor growth, or from a distinct carcinoma group, for which venous invasion is facilitated by proximity to the origin, is unclear. We analyzed the correlation between LM and venous invasion in patients with small IDCP tumors. Methods Of 388 patients who were diagnosed with IDCP, 20 (5.2%) had tumors with diameters Results The small-tumor group ( n  = 20) included 11 men and 9 women, aged 51–80 years. Five died of liver metastasis (LM group, n  = 5) and 15 patients (non-LM group, n  = 15) were either alive without recurrence ( n  = 11) or died of peritonitis carcinomatosa following local recurrence, subarachnoid hemorrhage, primary lung cancer, or old age ( n  = 1 for each cause of death). The LM and non-LM groups did not significantly differ in numbers of venous invasion by the carcinoma in IDCP and non-IDCP area of the pancreas. However, median numbers of invaded veins in the area of IDCP and percentage of invaded vein/total number of vein in IDCP area were significantly higher in the LM group. Conclusion Among patients with small IDCP tumors, the LM group showed more aggressive venous invasion by IDPC. Patients in whom ≥60% of veins were invaded by IDCP should be prepared for LM.