AIM:To evaluate the differences that exist between peripheral and mesenteric serum levels of carcinoembryonic antigen (CEA) and cytokeratins in patients with colorectal adenocarcinoma.METHODS:One hundred and thirty-eight patients with colorectal adenocarcinoma who underwent Gastroenterology of UNIFESP-EPM) between December 1993 and March 2000 were retrospectively analyzed.Differences between CEA and cytokeratin (TPA-M) levels in peripheral blood (P) and in mesenteric blood (M)were studied.Associations were investigated between peripheral and mesenteric levels and the staging and histopathological variables (degree of cell differentiation,macroscopic appearance,tumor dimensions and presence of lymphatic and venous invasion).RESULTS:Differences were observed in the numerical values of the marker levels:CEA (M) (39.10 mg/L +121.19 mg/L) vs CEA (P) (38.5 mg/L + 122.55 mg/L),P ＜ 0.05; TPA-M (N) (325.06 U/L + 527.29 U/L) vs TPA-M (P) (279.48 U/L + 455.81 U/L),P ＜ 0.01.The mesenteric CEA levels were higher in more advanced tumors (P ＜ 0.01),in vegetating lesions (34.44 mg/L±93.07 mg/L) (P ＜ 0.01) and with venous invasion (48.41 mg/L±129.86 mg/L) (P ＜ 0.05).Peripheral CEA was higher with more advanced staging (P ＜ 0.01)and in lesions with venous invasion (53.23 mg/L±158.57 mg/L) (P ＜ 0.05).The patients demonstrated increased mesenteric and peripheral TPA-M levels with more advanced tumors (P ＜ 0.01 and P ＜ 0.01) and in non-ulcerated lesions [530.45 U/L±997.46 U/L(P ＜ 0.05) and 457.95 U/L±811.36 U/L (P ＜ 0.01)].CONCLUSION:The mesenteric levels of the tumor markers CEA and cytokeratins were higher than the peripheral levels in these colorectal adenocarcinoma patients.Higher levels of these biologic tumor markers are associated with an advanced state of cancerous dissemination.