The average 5-year survival rate following resection of a ductal adenocarcinoma of the pancreas is 10%, worldwide. Despite increasing resection rates, only about 20% can be operated on with curative intent. A differential histopathological analysis of the resected tumors may help to justify expanding the surgical procedure by extended lymph-node dissection.Between January 1986 and December 1995, a total of 113 patients underwent resection with curative intent for a ductal pancreatic carcinoma with regional lymph-node dissection. All histological findings were reviewed and reclassified in accordance with the 1997 Union Internationale Contra la Cancrum (UICC) classification. Survival data for all of these patients were obtained from family doctors and registration offices. Independent prognostic factors were statistically analyzed.Of the 113 patients, 93 received an R0 resection. The postoperative mortality rate was 2.2% (2 of 93). More than one-half of the tumors had a diameter of between 2.1 cm and 4 cm. Among the 22 tumors measuring up to 2 cm in diameter, 41% already had lymph-node metastasis and 86% invasion of the lymphatic vessels. Carcinomas measuring between 4.1 cm and 6 cm were all associated with lymph-vessel invasion. Perineural invasion was present in 50% of the tumors. A noteworthy finding was the fact that 64% of the 25 tumors with negative lymph nodes had lymph-vessel invasion, and 48% perineural invasion. The cumulative 5-year survival rate of the R0-resected patients was 10. 5%. Patients with lymph-node-negative stages survived significantly longer (26.5%) than patients with lymph-node-positive stages (5%). Furthermore, a significant difference was seen between pN1a and pN1b (16.7% vs 2.2%). Multivariate analysis identified tumor grading, tumor size and lymph vessel invasion as independent prognostic factors.Apart from the factors tumor size and tumor grading, lymph-vessel invasion appears to be of special significance for the long-term prognosis. Already in the pN0 stage, the latter was present in 64% of the cases and must be considered a precursor of lymphogenic metastasization. Since lymph-vessel invasion was demonstrated in 86% of tumors measuring less than 2 cm, the therapeutic consequence for all ductal pancreatic tumors is an extended lymphatic and soft tissue dissection that goes beyond the regional lymph-node stations.