ABO blood group alleles and the risk of pancreatic cancer in a Japanese population

Several studies have investigated a possible association between the ABO blood group and the risk of pancreatic cancer (PC), but this association has not been fully evaluated in Asian populations. The present study aimed to assess the impact of genotype-derived ABO blood types, particularly ABO alleles, on the risk of PC in a Japanese population. We conducted a case-control study using 185 PC and 1465 control patients who visited Aichi Cancer Center in Nagoya, Japan. Using rs8176719 as a marker for the O allele, and rs8176746 and rs8176747 for the B allele, all participants' two ABO alleles were inferred. The impact of ABO blood type on PC risk was examined by multivariate analysis, with adjustment for potential confounders to estimate odds ratios (OR) and 95% confidence intervals (CI). An increased risk of PC was observed with the addition of any non-O allele (trend P = 0.012). Compared with subjects with the OO genotype, those with AO and BB genotypes had significantly increased OR of 1.67 (CI, 1.08-2.57) and 3.28 (CI, 1.38-7.80), respectively. Consistent with earlier reports showing a higher risk of PC for individuals with the non-O blood type, the previously reported protective allele (T) for rs505922 was found to be strongly correlated (r2 = 0.96) with the O allele. In conclusion, this case-control study showed a statistically significant association between ABO blood group and PC risk in a Japanese population. Further studies are necessary to define the mechanisms by which the ABO gene or closely linked genetic variants influence PC risk. (Cancer Sci 2011; 102: 1076-1080).