Smoking and serum CA19-9 levels according to Lewis and secretor genotypes

CA19-9, a marker for cancers of biliary tract, pancreas and colorectum, is not synthesized in those with no enzyme activity genotype (le/le) of Lewis (Le) gene. No enzyme activity genotype (se/se) of secretor (Se) gene is known to have an association with high serum CA19-9 levels. There are also variations in serum CA19-9 levels independent of the genotypes. This study aimed to examine the associations of serum CA19-9 levels with smoking, alcohol drinking and body mass index (BMI; kg/m²), after the adjustments of Le and Se genotypes. Subjects were 486 health check-up examinees (158 males and 328 females) aged from 39 to 90 years in Hokkaido, Japan. Genotyping was conducted for 3 polymorphisms; Le T59G (59T for Le allele and 59G for le allele), Se A385T (385A for Se allele and 385T for sej allele), and Se pseudogene (se5 allele). The genotypes of Le and Se were deterministic factors of serum CA19-9. Those with Le/Le & se/se had the highest mean, while CA19-9 was not detected or very low in those with le/le. Although no associations were observed with alcohol drinking and BMI, a significant association was observed with smoking. Among those with Le/Le, the geometric mean of CA19-9 was significantly lower for current smokers than for noncurrent smokers (p = 0.011 in 4-way ANOVA with age, sex and Se genotype). When hemoglobin A1c was further adjusted, the association became stronger (p = 0.0027). In addition to polymorphic variations, some components of cigarette smoke may influence the production or destruction of CA19-9.