MATSUNO, S., KOBARI, M., HISANO, H., YAMAUCHI, H. and SATO, T. Prognosis of the Pancreatic Cancer in Terms of the Regional Lymph Node Reaction. Tohoku J. exp. Med., 1985, 145 (3), 291-302 - In order to elucidate the immunological defense mechanism in tumor bearing host against pancreatic cancer, tissue reactions of the regional lymph nodes were investigated in terms of extension and prognosis of pancreatic cancer. As the site for investigation of lymph node, paracortical area, germinal center and sinus histiocytes system were selected. In each case paracortical hyperplasia, of hyperplasia germinal center and sinus histiocytosis were graded and the relationship between such grade and prognosis of resected pancreatic cancer was studied with the following results. The grades of each tissue reaction in cases without lymph node metastasis were higher than that observed in cases with metastasis. There was significant difference in sinus histiocytosis (p<0.01). Higher grade tissue reactions were observed in cases with primary lesion with histologic type classified as papillary adenocarcinoma or as well differentiated tubular adenocarcinoma as compared to those in cases of poorly differentiated histologic type. In cases with pancreatic cancer the prognosis was better than cases with higher grade of tissue reactions of the regional lymph nodes. In cases with pancreatic cancer both cellular immunity and humoral immunity are involved in host defense mechanism. It was considered that sinus histiocytosis is significant as an indicator for good prognosis and a factor to inhibit progression in pancreatic cancer.