Histopathologic and immunohistochemical studies on the elevation mechanism of carcinoembryonic antigen (CEA) in gastric cancer patients

Correlation between carcinoembryonic antigen (CEA) levels of peripheral and draining venous blood, and 11 histopathologic and 2 immunohistochemical variables, was examined in 53 gastric cancer patients and 8 patients with benign diseases. CEA levels of draining blood (with a mean of 136.5 ng/ml and positive rate greater than 5 ng/ml, 58, 3%) were significantly higher than those (30.3 ng/ml, 22.9%) of peripheral blood in patients with CEA producing cancer. However, CEA levels of draining blood were as low as 5 ng/ml and were not different from those of peripheral blood in all of the patients with CEA non-producing cancer and benign diseases. Elevation of CEA levels in draining and peripheral blood was most highly correlated with the venous invasion, although the levels in draining blood were related to other histopathologic variables including tumor size, macro- and microscopic types, invasive layer of gastric wall, peritoneal dissemination, liver and node metastasis, lymphatic invasion and stage classification except tumor location. These variables relating to CEA elevation in the blood were highly correlated with venous invasion. However, tumor location was not found the relation with venous invasion. These results suggest that CEA may be haematogenously drained by the portal system via the draining vein from the CEA producing cancer cells in the invasive veins but not by the thoracic duct of the lymphatic system, and that histopathologic CEA elevation-relating variables may affect secondarily the CEA elevation in the blood in association with the venous invasion.