Evaluation of Ca 12-5 as a tumor marker for gastric and colo-rectal cancer in comparison to CEA and Ca 19-9.

We performed simultaneous measurements of CA 12-5, CEA and Ca 19-9 in the preoperative sera of 87 patients with gastric cancer, 177 patients with colo-rectal cancer and 55 patients with benign diseases. 5.6% of the control patients, 13.8% of the gastric cancer patients and 9.6% of the colo-rectal cancer patients showed Ca 12-5 values of 27.0 U/ml and more. In contrast, the sensitivity of the tumor markers CEA (greater than or equal to 5.0 ng/ml in 17.1% of the gastric cancer and 36.2% of the colo-rectal cancer patients examined) and Ca 19-9 (greater than or equal to 25.0 U/ml in 16.1% of the gastric cancer and 19.8% of the colo-rectal cancer patients) was distinctly higher. The simultaneous determination of three markers on the one hand increased the rate of 'marker-positive' patients (up to 34.5% in gastric cancer and 45.2% in colo-rectal cancer) but on the other hand diminished the specificity (from 96.4% to 89.1%) of the examination.