[Clinical value of the CA 19-9 tumor marker with special reference to the Lewis phenotype].

BACKGROUND

Because of structure and biosynthesis of CA 19-9, it was postulated 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 cells showed elevated levels of this tumor marker.

PATIENTS AND METHOD

In 164 patients suffering from benign or malignant diseases both CA 19-9 and the Lewis phenotype were determined in sera. In addition in 51 patients red blood cells were tested for Lewis substances.

RESULTS

The frequencies of the different Lewis phenotypes on red blood cells were compared with the results found in sera. The prevalence of the phenotype 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 loss of Lewis substances on erythrocytes could be seen both in malignant and benign diseases. Only in patients with Lewis substances found in sera 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 concentrations of CA 19-9.