ABO and Cancer

As an illness, cancer has a huge global impact. Cancer patients are showing potential and dramatic responses to recent medications. Meanwhile, cancer genome projects have generated unprecedented insights into the cellular signalling pathways that spur the development and progression of cancer.

Every human carries a specific blood type. While everybody's blood constitutes the same elemental parts, there is some diversity in the kinds of blood that exist. ABO blood system is the best-known system for grouping blood types. These blood types are determined by carbohydrate moieties displayed on the surface of red blood cells (RBC) (Huang, J. Y et al, 2017). A basic test for these particular antigens (antigen A or B) can figure out an individual's blood type.

The relation between blood group and cancer was first suspected while interpreting the Shanghai cohort study, which was organized in 1986 (Huang, J. Y et al, 2017). The Cox proportional hazard models calculated hazard ratios for cancer and specific blood groups. One of the major conclusions of the study was that non-O blood type individuals had a greater risk for any of the cancers than the O blood type.

Since we inherit ABO blood type through genes, a genomewide association study noted an association between DNA sequence variants in the ABO locus and susceptibility to pancreatic cancer. The subjects so enrolled for the study were first interviewed in person by a trained research nurse using a structured questionnaire asking for advice on demographic characteristics, history of tobacco and alcohol use, and medical history. Part of the study design required the subjects to give a 10-ml blood sample and a single void urine specimen. The process of statistical analysis was 25 years of follow-up of the subjects' health status (Huang, J. Y et al, 2017). The results showed the most frequent diagnosis of cancer in the digestive system, which accounted for nearly 51% of total cancer cases. Combining the blood group data with the development of cancers of the gastrointestinal tract in an individual, it was found that individuals with non-A bloodtype were at nearly 20% lower risk than blood type-A. Compared with blood type-O, the non-O bloodtype had a higher risk of developing cancer. Therefore, the incidence of cancer was statistically different among different ABO blood types (Franchini Met al,2016).

It was found that individuals with non-A blood type were at lower risk than blood type-A by nearly 20%

The surprising part is that even after having such statistical results, the mechanism for the association is still not understood. Experimental studies have demonstrated that the expression of ABO blood antigens on colon tumor cells, and the cell proliferation and motility is highly associated with the expression of blood antigen A (Mao Y. et al, 2019). According to laboratory investigations, patients-derived hepatocellular tumor cells express blood-type antigens on their cell surface which has different patterns of expression than the non-tumorous adjacent cells (Mao Y. et al, 2019). This supports the thought of the role of ABO blood antigens in malignant transformation of hepatocytes (a type of cell found in the liver). Similarly, when studies were conducted on the transitional epithelium of bladder carcinoma, it was suspected that a reduction in the expression of antigen A was correlated with the invasiveness of the tumour (Liumbruno GM et al, 2013). To summarize the role of antigen, we can say that a n y alteration in these surface molecules may promote the transform of malignancy.

However, when we start looking for involvement of ABO blood system in diseases other than cancer, we often see a crowd of evidence: stronger associations, including a more pronounced hangover in blood group A individuals, better teeth in group O people, personality traits, intelligence traits, and digestion. Recent research has also carved out the role of ABO blood group antigens in neuroscience (Liumbruno GM et al, 2013).Since the studies conducted over the years had different experimental populations and small sample size, the heterogeneity among them can be expected. More experimental studies need larger study populations to get a better understanding of the mechanisms for the suspicious role of ABO blood groups in development. Thus, despite the latest technological and medical advances, cancer is still the leading cause of death, because we still don't understand its numerous intricate connections, and ABO blood group structure is just one of the many uncharted territories in cancer research.

REFERENCES

1. Huang, J. Y., Wang, R., Gao, Y. T., & Yuan, J. M. (2017). ABO blood type and the risk of cancer - Findings from the Shanghai Cohort Study. PloS one, 12(9), e0184295.

2. Franchini, M., Liumbruno, G. M., & Lippi, G. (2016). The prognostic value of ABO blood group in cancer patients. Blood transfusion = Trasfusione del sangue, 14(5), 434–440.

3. Liumbruno, G. M., & Franchini, M. (2013). Beyond immunohaematology : the role of the ABO blood group in human diseases. Blood transfusion = Trasfusione del sangue, 11(4), 491–499.

4. Mao, Y., Yang, W., Qi, Q. et al. Blood groups A and AB are associated with increased gastric cancer risk: evidence from a large genetic study and systematic review. BMC Cancer 19, 164 (2019).