The purpose of this study aims to investigate the influence of the ABO blood group on susceptibility to different pathological types of lung cancer. The results prove that after adjusting for age, sex, smoking, and drinking history, people with blood type O have a higher risk of lung cancer than people with blood type A. When looking into the different types of lung cancer, it turns out that people with blood type O have a higher risk of lung adenocarcinoma than people with blood type A. Furthermore, ABO blood group has no correlation with lung squamous cell carcinoma and small cell lung cancer.
The distribution of ABO blood group in China is characterized by a gradual decrease in the frequency of the B gene and an increase in the frequency of the O gene from north to south, with an increase in the frequency of the A gene in Yunnan, Guizhou, Sichuan, and the middle and lower reaches of the Yangtze. Overall, the blood group distribution in China is O>A>B>AB [9, 10]. However, in this experiment, the blood group distribution of the non-lung cancer control group was A>AB>B>O. This may be due to differences in geographical location and genetic factors. Nevertheless, the patients in the case group and the control group are of the same origin, and the blood group distribution in the case group and the control group largely coincides. Furthermore, the pathophysiological mechanisms between blood group and lung cancer do not change depending on the distribution of blood groups.
This study is not consistent with other relevant studies on the effect of the ABO blood group on the risk of lung cancer. These contradictions may be due to some factors: (1) most of the studies did not distinguish between the pathological types of lung cancer, or only a single pathological type of lung cancer was selected. However, the influence of blood group distribution on the different pathological types of lung cancer cannot be ignored. In view of this, many different pathological types were included in this study, and lung cancer with different pathological types was studied, respectively. What is more, cases with other pathological types were strictly excluded. The results are more reliable. (2) Each study’s sample size differs, and the results may differ. In this study, a larger sample size was adopted to reduce the error caused by the sample size.
The classification of ABO blood groups is determined by the A or B antigens on the surface of red blood cells . People with blood type A have only antigen A on their red blood cells, while people with blood type B have only antigen B on their red blood cells. People with blood type O have neither A nor B antigens in their red blood cells. In contrast, people with blood type AB have both A and B antigens. The gene, 9q34.1–34.2, encodes a blood group antigen-associated glycosyltransferase. However, A and B antigens are not only expressed on the surface of red blood cells but also on epithelial and endothelial cells and in lung tissues . They undertake the functions of cell adhesion, signal transduction, and transport . Studies have found that 9q34 contains proto-oncogene c-abl and human DNA repair gene XPA, and increased tumor susceptibility occurs when the above genes are mutated and lost . In addition, a large prospective cohort study found that increased glycosyltransferase activity corresponding to the ABO allele subtype was associated with an increased risk of pancreatic cancer . On the other hand, the underlying mechanisms associated with ABO blood group and tumorigenesis also include the body’s inflammatory state. ABO blood group has been found to be associated with circulating levels of TNF-α, soluble ICAM-1, e-selectin, and p-selectin [16,17,18]. This suggests that blood type may influence inflammation throughout the body and contribute to the development of cancer.
However, even if a certain genetic characteristic of the organism is susceptible to disease, such susceptibility will not be manifested without the effect of environmental factors . Smoking is a common cause of lung cancer. The Chinese prospective cohort study of chronic diseases carried out by Chen et al. included 500,000 subjects aged 30 to 79 years. The 7-year follow-up showed that the risk of lung cancer in male and female smokers was 2.51 and 2.28 times higher than that in nonsmokers, respectively . Among the specific types of lung cancer, squamous cell lung cancer and small cell lung cancer are greatly affected by smoking . This conclusion is consistent with the results of this study. The occurrence of lung cancer also has a certain relationship with gender. Men are more likely to develop lung squamous cell carcinoma and small cell carcinoma than women, and adenocarcinoma of the lung is less likely than women [22,23,24]. This conclusion is also consistent with the results of this study. The reason may be that gender is influenced by factors such as smoking and genetics . In addition, lung cancer is an aging disease to some extent. In the cell cycle of continuous replication, telomeres continue to shorten. Then, there is an increasing chance of DNA damage . Therefore, the risk of lung cancer increases gradually with age . The underlying mechanism needs to be further studied.
Shortcomings of this study are as follows:
The samples of this study are from a single-center retrospective study. Most of the cases were from Jiangxi province, with particular geographical limitations and single genetic background.
Staging analysis of patients with lung cancer was not performed.
Confounding factors, such as occupational carcinogenic factors, air pollution, diet, and physical activity, are not included in the study results, which may be biased.
Future multicenter, prospective studies are needed to verify the conclusions of this study.
In conclusion, the ABO blood group has a certain correlation with lung cancer in Jiangxi province. For different pathological types of lung cancer, people with blood type O have a higher risk of lung adenocarcinoma than those with blood type A. Squamous cell lung cancer and small cell lung cancer are not associated with blood type. The findings provide important clues for further research on lung cancer susceptibility.