Immunohistochemical study of genetic alterations in intraductal and invasive ductal tumors of the pancreas

Background/Aims: Multiple genetic alterations are involved in the developme nt of pancreatic neoplasm. Here we investigated the incidence of p53, ras, bcl-2 and c-erbB-2 gene alterations in intraductal papillary-mucinous tumor s and invasive ductal adenocarcinoma of the pancreas by immunohistochemical method to identify and analyze their relationship in terms of these geneti c alterations. Methodology: Fifty-four pancreatic lesions, including 18 benign (hyperplasi a (3) and intraductal papillary adenoma (15)), and 16 malignant (carcinoma in. situ (2) and intraductal papillary adenocarcinoma (14)) cases of intrad uctal papillary-mucinous tumor; and 20 cases of invasive ductal adenocarcin oma, were immunostained by avidin-biotin peroxidase conjugate method. Results: p53 and rasp21 expressions were significantly greater in malignant intraductal (P <0.01, P <0.05) and invasive ductal (P <0.01, P <0.01) tumo rs than in benign intraductal papillary-mucinous tumors; while bcl-2 and c- erbB-a expressions were significantly greater in invasive ductal adenocarci noma than both benign (P <0.01, P <0.05) and malignant (P <0.05, P <0.05) i ntraductal papillary-mucinous tumors. Conclusions: Different groups of genetic alterations are involved in differ ent phases of pancreatic tumorigenesis, p53 and ras gene alterations occur at an early stage during the development of intraductal papillary-mucinous tumor, while additional alterations of bcl-2 and c-erbB-2 occur during the development of invasive ductal adenocarcinoma of the pancreas.