AIM: To examine surgical specimens of pancreas with either chronic pancreatitis or pancreatic cancer in order to study whether ductal hyperplasia and dysplasia in pancreas represent precursor lesions for pancreatic cancer. METHODS: We examined expression of Ki-67, CEA, p53, and K-ras, in the surgical specimens of pancreas with adenocarcinomas (n= 11) and chronic pancreatitis (n = 12). Cellular proliferation was assessed by Ki-67 proliferation index using the proliferation marker Ki-67. In specimens with pancreas cancer, we divided pancreas epithelium into normal (n = 7), ductal hyperplasia (n = 3), dysplasia (n = 4), and cancerous lesion (n = 11) after hematoxylin and eosin staining, Ki-67, and CEA immunohistochemical staining. In cases with chronic pancreatitis, the specimen was pathologically examined as in cases with pancreas cancer, and they were also determined as normal (n = 10), ductal hyperplasia (n = 4), or dysplasia (n = 5). p53 and K-ras expression were also studied by immunohistochemical staining. RESULTS: In pancreatic cancer, the Ki-67 index was 3.73±3.58 in normal site, 6.62±4.39 in ductal hyperplasia, 13.47±4.02 in dysplasia and 37.03±10.05 in cancer tissue, respectively. Overall, p53 was positive in normal ducts, ductal hyperplasia, dysplasia, and carcinoma cells in 0 of 14 (0%), 0 of 7(0%), 7 of 9 (78%), and 10 of 11 (91%), respectively, and K-ras was positive in 0 of 8 (0%), 1 of 3 (33%), 4 of 6 (67%), 4 of 5 (80%), respectively. CONCLUSION: Our results favorably support the hypothesis that ductal hyperplasia and dysplasia of the pancreas might be precursor lesions for pancreas cancer. Further evaluation of oncogenes by the molecular study is needed. AIM: To examine surgical specimens of pancreas with either chronic pancreatitis or pancreatic cancer in order to study whether ductal hyperplasia and dysplasia in pancreas represent precursor lesions for pancreatic cancer. METHODS: We examined expression of Ki-67, CEA, p53, and K- ras, in the surgical specimens of pancreas with adenocarcinomas (n = 11) and chronic pancreatitis (n = 12). Cellular proliferation was assessed by Ki-67 proliferation index using the proliferation marker Ki-67. (n = 3), dysplasia (n = 4), and cancerous lesion (n = 11) after hematoxylin and eosin staining, Ki-67, and CEA immunohistochemical staining. In cases with chronic pancreatitis, the specimen was pathologically examined as in cases with pancreas cancer, and they were also determined as normal (n = 10), ductal hyperplasia (n = 4), or dysplasia (n = 5) expression were also studied by immun ohistochemical staining. RESULTS: In pancreatic cancer, the Ki-67 index was 3.73 ± 3.58 in normal site, 6.62 ± 4.39 in ductal hyperplasia, 13.47 ± 4.02 in dysplasia and 37.03 ± 10.05 in cancer tissue, respectively. Overall, p53 was positive in normal ducts, ductal hyperplasia, dysplasia, and carcinoma cells in 0 of 14 (0%), 0 of 7 (0%), 7 of 9 (78%), and 10 of 11 CONCLUSION: Our results favorably support the hypothesis that ductal hyperplasia and ras was positive in 0 of 8 (0%), 1 of 3 (33%), 4 of 6 (67%), 4 of 5 (80%), respectively. dysplasia of the pancreas might be precursor lesions for pancreas cancer. Further evaluation of oncogenes by the molecular study is needed.