OBJECTIVES Invasive intraductal papillary mucinous neoplasm (IPMN) of the pancreas is often considered to have a better prognosis than pancreatic ductal adenocarcinoma. The aim of this study was to evaluate and compare the prognosis and clinicopathologic features between 2 groups.

METHODS Clinicopathologic features and long-term outcome of 32 patients with invasive IPMN were retrospectively evaluated and compared with those of 332 patients with pancreatic ductal adenocarcinoma.

RESULTS Asymptomatic patients were more frequently observed in the group of invasive IPMN than ductal adenocarcinoma (28% vs 11%, P = 0.013). The distribution of stages of invasive IPMN was as follows: stage I (n = 10, 31%), II (n = 8, 25%), III (n = 3, 9%), and IV (n = 11, 34%). Among 19 patients who underwent resection for invasive IPMN, 10 (53%), 1 (5%), 1 (5%), and 2 (11%) had T1 stage tumors and tumor with lymph node metastasis, lymphatic, and perineural invasions, respectively, which were significantly infrequently observed compared with those with ductal adenocarcinoma. The 5-year survival rate of invasive IPMN was 33.9% compared with 9% of ductal adenocarcinoma (P = 0.011). The difference in the mean survival rates between invasive IPMN and ductal adenocarcinoma in patients without metastasis was also significant but not in patients with metastasis. During the median follow-up period of 18.4 months, 3 patients (16%) had a recurrence after resection for invasive IPMN.

CONCLUSIONS Both the less aggressive pathological factors concerned with tumor invasiveness and early diagnosis of invasive IPMN contribute to higher survival rates of invasive IPMN than ductal adenocarcinoma. However, the prognosis of metastatic invasive IPMN is as poor as that of ductal adenocarcinoma.