THE CLINICAL RELEVANCE OF THE TUMOR-MARKE R CA-19-9 WITH SPECIAL REFERENCE TO THE LEWIS PHENOTYPE

Background: Because of structure and biosynthesis of CA 19-9 it was po stulated, that patients with the Lewis phenotype Le(a-b-) are not able to synthesize CA 19-9. But some patients with Le(a-b-) on red blood c ells showed elevated levels of this tumor marker. Patients and method: In 164 patients suffering from benign or malignant diseases both CA 1 9-9 and the Lewis phenotype were determined in sera. In addition in 51 patients red blood cells were tested for Lewis substances. Results: T he frequencies of the different Lewis phenotypes on red blood cells we re compared with the results found in sera. The prevalence of the phen otype Le(a-b-) on erythrocytes was significantly higher than in sera. In 51 patients both determinations were performed. These results were compared additionally. The phenotype Le(a-b-) found on red blood cells agreed with the results found in sera only in 30% of the cases. A los s of Lewis substances on erythrocytes could be seen both in malignant and benign diseases. Only in patients with Lewis substances found in s era elevated levels of CA 19-9 could be seen. Conclusion: Considering only the Lewis phenotype in sera it could be confirmed, that patients with the genotype Le(a-b-) are not able to express elevated concentrat ions of CA 19-9.