A critical comparison of the value of pregnancy-associated alpha2-glycoprotein and carcinoembryonic antigen assays in patients with colorectal cancer.

Absolute serum concentrations of pregnancy-associated alpha2-glycoprotein (alpha2-PAG) and carcinoembryonic antigen (CEA) were compared in 54 patients before and after surgery for colorectal cancer. Preoperatively, elevated levels of alpha2-PAG were found in 32 (59%) and of CEA in 35 (65%). Postoperatively, elevated alpha2-PAG levels were found in 10 of 18 patients (56%) without clinical evidence of recurrence whereas elevated CEA levels were present in three (16%). In patients who developed clinical evidence of tumour recurrence, alpha2-PAG levels were elevated in 8 of 13 (62%) while CEA levels were uniformly abnormal. It is concluded that, in this cross-sectional study, measurement of alpha2-PAG concentrations is less reliable than CEA in the detection of tumour recurrence after apparently curative surgery for colorectal cancer.