We think that defining the potential relationship between ABO blood groups and cancer development is of great importance in terms of public health. If a relationship is determined, this can change the course of cancer screening programs. Based on this, several studies have been conducted on this subject, and a relationship between many cancer types and blood groups has been shown [13,14,15,16]. However, it should be noted that the distribution of ABO blood groups may differ throughout the world population . This study investigated whether ABO blood groups have a role in MM etiology. In addition, we evaluated the prognostic significance of ABO blood groups that may affect disease-specific clinical findings and survival.
In previous studies, in addition to solid organ tumors, the association of hematological malignancies such as lymphoma and leukemia with ABO blood groups was also investigated [15, 18]. In a study, it was found that the incidence of blood group 0 was higher in patients with acute lymphoblastic leukemia and that the incidence of blood group A was lower in patients with Hodgkin lymphoma and non-Hodgkin lymphoma . However, in the same study, there was no relationship between blood groups and the disease in acute myeloid leukemia patients . In another study, there was no difference between the ABO blood group distribution in lymphoma patients and the normal population . In our study, we found that the frequency of blood group 0 in MM patients was significantly lower than in the normal population. Based on this result, we have found that having blood group 0 is a protective factor for MM development compared to having other blood groups. The direct mechanism of the effect of ABO blood group system on cancer development has not been clearly elucidated in the studies conducted so far. However, there are many theories about this relationship. In many types of cancer, ABO gene is encoded in the region of chromosome 9q34.2 where genetic changes are common . The three variant alleles (A, B and O) of a single gene on this chromosome determine a person’s blood type by encoding three different glycosyltransferase with different substrate specificities. It is known that dysregulation in ABO glycosyltransferase activity plays a key role in carcinogenesis due to its effect on cell proliferation, tumor invasion, host immune response and metastatic spread . It is thought that dysregulation of the enzymatic activities of glycosyltransferase A and B may result in increased plasma levels of von Willebrand factor and the risk of venous thromboembolism, leading to angiogenesis, apoptosis and tumor formation . These hypotheses aim to explain why the incidence of cancer is lower in blood group 0, as in our study. However, in many studies, there was no relationship between ABO blood group system and cancer development, or there was no significant risk reduction in cancer development in all cancer types in blood group 0. This suggests that there are various mechanisms between the ABO blood group system and cancer development.
This study found no relationship between the ABO blood group system and common laboratory and clinical findings in MM patients such as anemia, renal failure, hypercalcemia and lytic lesions. In our study, the incidence of extramedullary lesion was 15.1% in the whole patient population. Varettoni et al. found that the prevalence of extramedullary lesion was 13%, similar to our study . It is not known why some people only have solitary extramedullary lesions, while some people also develop multiple myeloma. However, while some MM patients develop extramedullary lesions, the mechanism of its absence has not been explained. It is thought to be associated with the differences in cellular adhesion molecules or chemokine receptor expression profiles of malignant plasma cells . Our study examined the relationship between blood groups and the incidence of extramedullary lesions in MM patients and found that having blood group 0 was a predisposing factor for extramedullary lesion development.
Serum LDH level was significantly higher in MM patients with blood group 0 compared to MM patients with other blood groups. Serum LDH levels above normal indicate that the disease will be aggressive and that the proliferation rate is high . However, it has also been demonstrated that high serum LDH levels may be associated with an extramedullary lesion in MM patients . In our study, we found that blood group 0 was associated with both high serum LDH levels and high prevalence of extramedullary lesions. We think that higher prevalence of extramedullary lesions in this blood group may have contributed to the significantly higher serum LDH level in blood group 0.
Our study evaluated the prognostic significance of blood groups in MM patients. Overall survival was significantly shorter in patients with blood group 0. These results show that ABO blood group has a strong prognostic value in MM patients. Osada et al. showed in their study that ABO blood group system had a prognostic significance in lymphoma patients . However, OS was significantly shorter in patients with group B in this study. In another study of patients with pancreatic cancer, the median OS was significantly longer in patients with blood type 0 than in patients with non‑0 blood groups (A, B, and AB) . All these studies show that different blood groups have prognostic importance in different types of cancer. However, the mechanism that causes this difference is unknown.
The retrospective nature of our study was the most important limiting factor. However, there was a sufficient number of patients to obtain consistent results in all blood groups.
In conclusion, individuals with blood group 0 had a lower risk of developing MM in this study. It was determined that having blood group 0 in MM patients was a predisposing factor for the development of extramedullary lesions, and that these patients had high serum LDH levels. In addition, it was shown that having blood group 0 was a very important prognostic factor for MM patients and was associated with short OS. Although there was a relationship between ABO blood group system and the development of MM and OS, additional studies are needed to explain the mechanism of this relationship.