LEWIS AND SECRETOR GENE DOSAGES AFFECT CA19-9 AND DU-PAN-2 SERUM LEVELS IN NORMAL INDIVIDUALS AND COLORECTAL-CANCER PATIENTS

The effect of doses of the secretor (Se) and Lewis (Le) genes on the s erum levels of CA19-9 and DU-PAN-2 was investigated in 400 normal indi viduals. It was clearly demonstrated that the Se gene dosage negativel y affected both the CA19-9 and DU-PAN-2 values, whereas the Le gene do sage positively affected the CA19-9 value and negatively affected the DU-P4N-2 value. The 400 normal individuals were separated into nine gr oups hy their Le and Se genotypes, as follows: group 1, Le/Le and se/s e; group 2, Le/le and se/se; group 3, Le/Le and Se/se; group 4, Le/le and Se/se; group 5, Le/Le and Se/Se; group 6, Le/le and Se/Se; group 7 , le/le and se/se; group 8, le/le and Se/se; and group 9, le/le and Se /Se. The group 1 individuals, having homozygous inactive Se alleles (s e/se) and homozygous active Le alleles (Le/Le), exhibited the highest mean CA19-9 value, The CA19-9 value clearly ranged from a high in grou p 1 to a low in group 9. All of the Le-negative individuals who had th e le/le genotype (groups 7, 8, and 9) had completely negative CA19-9 v alues, i.e., under 1.0 unit/ml, irrespective of the Se genotype. Group 7 individuals (le/le and se/se) shelved a higher mean DU-PAN-2 value than did individuals in other groups. The Le-negative individuals in g roups 8 and 9 also showed a higher mean DU-PAN-2 value than did the Le -positive individuals in groups 1-6. We recommend that the revised Le and Se genotype-dependent positive/negative cutoff values for CA19-9 a nd DU-PAN-2, determined in this study, be applied for more accurate ca ncer diagnoses. The Le and Se genotypes of 168 patients with colorecta l cancer were also examined, and the CA19-9 and DU-PAN-2 values were m easured before surgical resection. All 15 Le-negative patients (le/le) with colorectal cancer again showed undetectable CA19-9 values, i.e., under 1.0 unit/ml, but many of them exhibited highly positive DU-PAN- 2 values. In contrast, many of the Le-positive patients (Le/le or Le/l e) had positive CA19-9 values, whereas very few of them exhibited posi tive DU-PAN-2 values. CA19-9 measurement is more useful than is DU-PAN -2 measurement for Le-positive patients, but it is not useful for Le-n egative ones. DU-PAN-2 measurement should be performed in Le-negative patients for cancer diagnosis.