This study investigates the presence of specific tumor antigens in human digestive system cancers and their potential relationship to embryonic development. The authors previously identified two tumor-specific antigens in colonic carcinomas. This study aimed to determine if these antigens were present in other adult and fetal tissues. Using immuno-diffusion techniques, they found that the antigens were present in all tested primary and metastatic carcinomas of the digestive system, but not in other adult tissues or benign tumors. In fetal tissues, these antigens were detected in gut, liver, and pancreas between 2 and 6 months of gestation. The authors propose that these antigens, named "carcinoembryonic" antigens, represent system-specific cancer antigens of the human digestive system, which are repressed during normal tissue differentiation but reappear in malignant cells through a process of derepressive-dedifferentiation. This suggests a link between embryonic development and the emergence of tumor-specific antigens in cancer cells.This study investigates the presence of specific tumor antigens in human digestive system cancers and their potential relationship to embryonic development. The authors previously identified two tumor-specific antigens in colonic carcinomas. This study aimed to determine if these antigens were present in other adult and fetal tissues. Using immuno-diffusion techniques, they found that the antigens were present in all tested primary and metastatic carcinomas of the digestive system, but not in other adult tissues or benign tumors. In fetal tissues, these antigens were detected in gut, liver, and pancreas between 2 and 6 months of gestation. The authors propose that these antigens, named "carcinoembryonic" antigens, represent system-specific cancer antigens of the human digestive system, which are repressed during normal tissue differentiation but reappear in malignant cells through a process of derepressive-dedifferentiation. This suggests a link between embryonic development and the emergence of tumor-specific antigens in cancer cells.