ABO Blood Group and the Risk of Pancreatic Neoplasms in Chinese Han Population: A Study at Shanghai Pancreatic Cancer Institute.

To the Editor:

Pancreatic cancer is one of the most aggressive cancers.[1] Accumulating epidemiological studies suggested a link between human blood group antigens and carcinogenesis or progression of various human tumors including pancreatic cancer. So far, there are few large studies of this kind in China. To understand more about the relationship between ABO blood group and the risk of developing pancreatic cancer, we collected data from pancreatic cancer patients of the Han Chinese people diagnosed in our institution between February 1, 2010, and May 31, 2017, and evaluated whether ABO blood type was a risk factor for pancreatic cancer. Meanwhile, we investigated whether there is a link between ABO blood group and pancreatic neuroendocrine tumors (pNETs) and other types of pancreatic masses. In addition, correlations between ABO blood group and carbohydrate antigen (CA) 19-9, CA 125, and carcinoembryonic antigen (CEA) were also investigated.

We included patients with definite pathological diagnosis and blood types. The results of CA 19-9, CA 125, and CEA were collected within 1 week before surgery or puncture. Because there are no authoritative reports describing the definite distribution ratios of different blood types in Han Chinese people, we quoted the data reported by Sun et al,[2] which included up to 200,660 Han Chinese people, as the control group in our study.

In total, 4099 patients were eligible for this analysis, including 3063 cases of pancreatic cancer, 222 cases of pNETs, and 814 cases of other types of pancreatic masses. Distributions of ABO blood types were displayed in the form of pie charts in Figure 1. The odd ratio (OR) and 95% confidence intervals (CIs) for pancreatic cancer, pNETs, and other types of pancreatic masses by ABO blood group were listed in Table 1, and blood type O was used as the referent group. For the combined study population, compared with patients with blood group O, those with blood group A were more likely to develop pancreatic cancer (OR for incident pancreatic cancer, 1.522 [95% CI, 1.388–1.668], P < 0.001), whereas those with blood group B were less likely to develop pNETs and other types of pancreatic masses (OR for incident pNETs and other types of pancreatic masses, 0.620 [95% CI, 0.430–0.894], 0.711 [95% CI, 0.593–0.852], P = 0.01 and P < 0.001, respectively). The levels of CA 19-9 and CA 125 in pancreatic cancer patients did not differ significantly between different blood groups (P = 0.779 and P = 0.253, respectively), whereas the rate of elevated expression of CEA was significantly lower in pancreatic cancer patients with blood type A than those with blood types B, AB, and O (P < 0.001, P = 0.031, and P = 0.027, respectively).

FIGURE 1

Distributions of ABO blood types in people of different subgroups. A, Pancreatic cancer, (B) pNETs, (C) other types of pancreatic masses, and (D) patients discharged from Peking Union Medical College Hospital (Beijing, China) between January 2010 and June 2016.

TABLE 1

Odds Ratios and 95% Confidence Intervals for Different Patients With Pancreatic Cancer, pNETs, and Other Types of Pancreatic Masses by ABO Blood Group

The ABO blood group system was first discovered more than one century ago, and until now, it is still the most important blood group system in immunohematology, transfusion, and transplantation medicine.[3] In recent years, there is increasing evidence of an important role of ABO blood group system in pancreatic cancer. In this study, we reported the blood group distributions of patients with pancreatic cancer in our center, and we found that there is an association between ABO blood type and pancreatic cancer in Han Chinese people. Han Chinese people with blood type A had an increased likelihood of developing pancreatic cancer than people with blood type O, which is in accordance with the study by Wolpin et al.[4] However, unlike the results of Wolpin et al,[4] our study revealed that the risks of pancreatic cancer in blood types B and AB were similar to that of blood type O. In fact, the results were not exactly the same between other previous reports either.[5,6] This may be owing to racial and ethnic differences in blood type distributions.

A number of studies have investigated the mechanisms of how blood type affects pancreatic cancer. Hofmann et al[7] reported that blood group IgM isoagglutinins and O-GalNAc glycoproteins may play a role in the pathogenesis and progression of pancreatic cancer, and it was reported that ABO antigen expression is indeed altered in primary and metastatic pancreatic cancers compared with normal pancreatic tissues.[8] In addition, large amounts of reports suggest that there is a link between blood group antigens and the systemic inflammatory response,[9] which has been demonstrated to be important mechanisms during the initiation and development of tumors, including pancreatic cancer. However, more studies on this issue are still warranted to explore the underlying mechanisms involved.

Overall, our findings confirmed once again that the ABO blood group was associated with the risk of pancreatic cancer from the perspective of the Han Chinese people. This will help to identify high-risk population subsets of pancreatic neoplasms in China. In addition, clarifying the etiology mechanisms linking pancreatic cancer risk to ABO blood group may provide a new perspective for the treatment of pancreatic cancer.