Relationship between ABO Blood Group Antigens and Pancreatic Cancer-Systemic Review

Pancreatic cancer is among the most aggressive types of cancer. It has mortality rates as the seventh most frequent cause of cancer death worldwide. The association between ABO blood group and risk of pancreatic cancer has been known for more than 40 years.Various studies, in detail, although conflicting on many occasions, on large population groups, cohort studies, case-control studies, retrospective comparative studies, and meta-analysis all provide a systematic knowledge on cancer and human ABO blood groups. Population studies were compared among pancreatic cancer cases and nested controls. All participants were selected according to certain routine factors to emphasize an important point in the selection of population controls. Studies showed statistically distinct distribution of blood groups in different regions and different ABO frequencies in those populations was studied and combined without introducing bias providing evidence of associations of cancer of the pancreas with the ABO blood groups. Evidence exists that there is an increased risk of pancreatic cancer among blood group B individuals and a modest excess risk for pancreatic cancer in blood group A individuals. pancreatic cancer susceptibility loci is identified in ABO gene. ABO blood group alleles represent a common, partially penetrant genetic determinant for pancreatic cancer. ABO blood group genes are mapped at 9q34.2 region in which genetic alteration is common in pancreatic cancer. The authors of various studies suggested a role of ABO glycosyltransferase specificity in pancreatic tumorigenesis. The hypothesis that ABO glycosyltransferase activity influences pancreatic cancer risk was simultaneously confirmed by many. GWAS (genome-wide association study) identified pancreatic cancer susceptibility loci in the ABO gene and an increase in risk was noted with the addition of each non-O allele, thus supporting earlier epidemiological evidence that people with blood group O may have a lower risk of pancreatic cancer than those with groups A, B or AB. Future studies should examine the mechanism linking pancreatic cancer risk to ABO blood group. KeywordsABO Blood group, pancreatic adenocarcinoma, glycosyltransferase, risk factor, genome. INTRODUCTION In India, cancer has become one of the leading causes of death. The association between inherited blood group and the risk of various malignancies has been dealt with in detail by many authors, reasons being, ABO blood groups are a stable feature of population and they differ among various groups. Various studies, in detail, on large population groups, cohort studies, case-control studies, and meta-analysis all provide a systematic knowledge on cancer and human ABO blood groups. In the early 20th century Dr. Karl Landsteiner identified three blood groups. A single gene on chromosome 9q34 and its nucleotide sequence, found to define a person's blood group, was elucidated in 1990. The ABO gene encodes a glycosyltransferase with three main variant alleles (A, B, and O), with different substrate specificities. The A, B, and O glycosyltransferases transfer N-acetylgalactosamine, D-galactose, and no sugar residue, respectively, to a protein backbone, known as the H antigen, which is expressed on the surface of RBC and numerous other tissues throughout the body. In laboratory investigations, patient-derived pancreatic cancer cells have different patterns of expression of blood group antigens on their cell surface than cells in adjacent normal pancreatic ducts , suggesting that modifications to glycosyltransferase specificity occur during pancreatic tumorigenesis. Alterations in surface glycoconjugates thought to lead to modifications in intercellular adhesion, membrane signaling, and immunosurveillance, that influence tumor development and spread . Human pancreatic cancer has shown to express either A or B antigens corresponding to the individual blood group or lose blood group antigen expression. Deletion of A, B, H or Lewis antigens and incompatible expression of A or B antigens were seen as cancer-associated in the pancreas. Incompatible expression of blood grouprelated antigens was observed in pancreatic cancer cells, compared with patient blood group type, indicating that Lewis antigen expression in pancreatic cancer independent of the blood group phenotype and may be useful as a tumor marker. A correlation of blood group antigen expression in tumors with metastasis and prognosis had been reported for various human malignancies and the loss or presence of human blood group antigens can increase the expression of certain blood group carbohydrate antigens on the surface of cancer cells that can be useful prognostic and diagnostic markers as is the appearance and disappearance of blood type antigen hallmarking malignancies. HISTORY The relationship between ABO blood group and risk of pancreatic cancer has been known for more than 4 decades, and yet has received little attention. In 1960, Aird et al. carried out a study in the United Kingdom and detected "evidence of some strength that cancer of the pancreas is commoner in persons of group A than in persons of groups S.Samyukta et al /J. Pharm. Sci. & Res. Vol. 7(5), 2015, 260-265