[Clinical significance of the circulating tumor-associated antigen CA 19-9 in cancers of the digestive tract].

The relevance of the tumour associated antigen CA 19-9, defined by a monoclonal antibody, was investigated in 471 patients with carcinomas of the gastrointestinal tract and in 100 patients with benign diseases of the abdomen. In the early stages of gastric and colorectal carcinomas the sensitivity of the CA 19-9 test was between 10 and 25% and increased to about 50% in tumour stage IV. Detection rate in pancreatic carcinoma was 88% and thus markedly higher. The specificity of the test, as against the group of benign abdominal diseases, was 95%. Postoperative CA 19-9 follow-up showed unaltered individual baseline values in 192 out of 196 cases without clinical evidence of tumour progression. However, in 40 out of 61 cases (66%) with recurrencies or metastases continuous increases of CA 19-9 were observed which preceded the clinical relapse by up to 16 months (median 2 months). Concomitant determination of CEA increased sensitivity to 90% due to partial complementary information. This was particularly pronounced in gastric carcinomas in whom continuous increases of CEA involved only 58% of all patients with tumour progression. By simultaneous determination of both tumour markers this ratio rose by increases of both or one antigen to 83%.