Increased concentrations of genotype-interpreted Ca 19-9 in urine of bladder cancer patients mark diffuse atypia of the urothelium

We investigated the use of genotype-interpreted measurements of the tumor marker Ca 19-9 in the urine of bladder cancer patients as a marker of the extent of urothelial disease. Ca 19-9 in urine (sialyl-Le(a)/creatinine ratio) was measured in 81 bladder cancer patients and correlated to T-category, histologic grade, and presence of urothelial dysplasia. As reference group, Ca 19-9 ratio was measured in urine from 21 apparently healthy individuals. The amount of sialyl-Le(a) expressed is influenced by the Lewis genotype and secretor status. Accordingly, secretor status was determined in urine by a novel ELISA method, and the Lewis genotypes of all of the individuals were determined by PCR cleavage methods. Ca 19-9 concentrations in urine were higher (P < 0.01) in bladder cancer patients than in healthy individuals and significantly (P = 0.02) higher in cancer patients with concomitant urothelial dysplasia than in those with normal urothelium. For individuals Lewis-genotyped as homozygous wild-type, Ca 19-9 concentrations in urine were higher, both in cancer patients (P = 0.06) and in healthy individuals (P = 0.004), than in the heterozygous individuals. Furthermore, nonsecretor cancer patients had higher (P < 0.01) Ca 19-9 concentrations in urine. Attention is drawn to the possibility of a general genotype interpretation of a result in clinical chemistry.