Prediction of invasive carcinoma in branch type intraductal papillary mucinous neoplasms of the pancreas

Background Patients with branch duct type intraductal papillary mucinous neoplasm (BD-IPMN) without invasion usually show favorable prognosis. However, the prognosis becomes poor when the IPMN lesions give rise to invasive carcinoma cells. In addition, recent studies have revealed that BD-IPMN is frequently complicated by common type pancreatic ductal carcinoma. Thus, the prognosis of BD-IPMN depends on the occurrence of these two types of invasive carcinoma. However, little is known about the risk factors for the development of these invasive carcinomas in BD-IPMN. This study aims to identify the factors which predict the development of invasive carcinoma in BD-IPMN. Methods Invasive pancreatic carcinoma associating with BD-IPMN was classified as invasive IPMN group (invasive carcinoma derived directly from IPMN lesions) and concomitant group (common type of invasive carcinoma concomitant with BD-IPMN). The relation between the incidence of each type of invasive carcinoma in BD-IPMN and the clinicopathological parameters was retrospectively analyzed. Results There were 12 patients with invasive IPMN and 7 patients with concomitant cancer in 159 patients with BD-IPMN. Diameter of dilated branch (P < 0.001) or main pancreatic duct (MPD) (P = 0.001), size of mural nodule (P < 0.001), serum CEA level (P < 0.001) and serum CA19-9 level (P < 0.001) were factors associated significantly with invasive IPMN by univariate analysis. Among these factors, mural nodule with size larger than 6.5 mm [odds ratio 14.86 (95% CI 1.37-60.45); P = 0.02] and serum carcinoembryonic antigen (CEA) level over 5 ng/ml [odds ratio 6.91 (95% CI 1.17-54.13); P = 0.03] were found to be the factors independently associated with invasive IPMN. On the other hand, both univariate and multivariate analyses revealed that elevated carbohydrate antigen 19-9 (CA 19-9) levels were associated with the occurrence of concomitant ductal carcinoma in BD-IPMN [odds ratio 10.31 (95% CI 1.77-81.51); P = 0.01]. Conclusions Our results suggested that careful imaging study of the entire pancreas in addition to tumor lesions and measurement of serum CEA and CA19-9 would be required to find out the development of the two types of invasive carcinoma in BD-IPMN.