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Why does Helicobacter pylori increase risks of colorectal cancer?
The relationship between Helicobacter pylori infection and gastric cancer has long been recognized. In recent years, many studies have shown that Helicobacter pylori infection is also related to the incidence of colorectal tumors.
Not long ago, a patient with Helicobacter pylori infection on physical examination came to see a doctor. The patient had no obvious gastrointestinal symptoms and no family history of tumors. Considering that the patient is over 50 years old, it is recommended that the patient undergo routine gastrointestinal endoscopy. Gastroscopy revealed that the patient had chronic atrophic gastritis.
Colonoscopy revealed that the patient had multiple polyps in the colon. One of the polyps had already developed focal early cancer. Because of the timely detection, the patient’s tumor can still be treated by endoscopic resection.
In recent years, there have been many patients who have come to see a doctor. They have undergone colonoscopy due to the discovery of Helicobacter pylori infection. They have been found to have colon polyps or colon cancer. Even some patients’ tumors are already advanced tumors when they are found.
Multiple studies have confirmed that Hp infection is associated with the risk of colorectal cancer
1. A study by researchers from the Duke Cancer Institute (DCI), published in the October 2018 issue of Gastroenterology, discussed the relationship between Helicobacter pylori antibodies and increased colon The relationship between the risk of rectal cancer.
In an analysis of more than 4000 cases of colorectal cancer, researchers selected from a large number of different cohort studies and found that the incidence of colorectal cancer is related to infection with a certain virulent strain of Helicobacter pylori (H. pylori) There is a significant correlation between the population of people, especially African Americans.
Dr. Meira Epplein, the first author of the study and co-head of DCI cancer control and population sciences, said and his colleagues collected data from 10 large regional and national studies, including the Southern Community Cohort Study, the Nurses’ Health Study, and the Women’s Health Initiative. And the American Cancer Society Cancer Prevention Research. They analyzed the blood samples of more than 8,400 study participants from different races and regions. Half of them later developed colorectal cancer and the other half did not.
The researchers found that Helicobacter pylori infection was equally common in the cancer and non-cancer groups, and 4 out of 10 patients in the two groups were positive for exposure to the bacteria. But there are also obvious racial differences. The rate of Helicobacter pylori infection in white patients is below average, and the rate of infection in Asian Americans is below average.
However, for black and Latino patients, this proportion is much higher. Among African Americans, 65% of non-cancer patients and 71% of colorectal cancer patients have antibodies to Helicobacter pylori. Among Latin Americans, 77% of non-cancer groups and 74% of cancer groups have antibodies.
Further analysis found that the four Helicobacter pylori protein antibodies are the most common in different colorectal cancer populations. In this study, a Helicobacter pylori protein, VacA, is most closely linked to the increased risk of colorectal cancer in African Americans. In particular, high levels of antibodies to this protein are associated with African Americans and sub- The incidence of colorectal cancer among African Americans is related.
Epplein said that if the Helicobacter pylori VacA protein does not directly cause cancer, additional studies may also determine whether its antibodies can be used as a marker of colorectal cancer risk.
“Oncology” January 15, 2019 Link to the original text:
2. In Germany, Zhang et al. evaluated the relationship between Helicobacter pylori serovar and the risk of colorectal cancer in a large case-control study in Germany from 2003 to 2007.
In 1712 cases of colorectal cancer patients and 1669 cases of control group, serum Helicobacter pylori antibody and cytotoxin-related gene A protein (CagA) were detected. Logistic regression was used to estimate the relationship between Helicobacter pylori serological value and the risk of colorectal cancer, and the potential confounding factors and stratification were adjusted according to age, gender, anatomical subtype and cancer stage.
In general, the serum response value of Helicobacter pylori in the case group (46.1%) was higher than that in the control group (40.1%), resulting in an age- and gender-adjusted odds ratio of 1.30 (95% confidence interval (CI): 1.14, 1.50) ). After adjusting the established risk factors for colorectal cancer, the odds ratio decreased to 1.26 (95% CI: 1.09, 1.47) and further decreased to 1.18 (95% CI: 1.01, 1.38). Stratified analysis showed that the increased risk was mainly confined to left colorectal cancer, with an odds ratio of 1.22 (95% CI: 1.02, 1.45), suggesting that Helicobacter pylori infection may be less related to colorectal cancer, but the left side The incidence of rectal cancer is associated with an increased risk.
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3. In recent years, many domestic scholars have reported the relationship between Hp infection and colorectal cancer.
Gao Feng and other studies showed that the Hp infection rate of the colorectal cancer group was higher than that of the normal colonoscopy group (P<0.01), and the risk of colorectal cancer caused by Hp infection was 2.66 times that of the non-Hp infection group.
Research by Zhang et al. showed that Hp infection increased the risk of colorectal cancer (OR=1.30, 95%CI=1.14-1.50). A correction analysis of age, gender, smoking, lifestyle, education, economic level and other factors showed that the OR value was reduced to 1.26 ( 95%CI=1.09～1.47), suggesting that Hp is only one of the risk factors in the occurrence of colorectal cancer. The occurrence of colorectal cancer is caused by the combined effect of multiple factors including environmental factors; the stratified analysis of colorectal cancer at different stages shows that HP Infection increases the risk of early colorectal cancer (stage I + II).
4. There are 2 meta-analysis results published in 2013 that included 22 and 28 clinical studies, respectively, showing that:
The incidence of colon polyps and colon cancer in patients with Helicobacter pylori infection increases, that is, Helicobacter pylori infection increases the risk of colon adenoma and colon cancer.
The analysis data from NIH also showed that Helicobacter pylori infection is related to the occurrence of colorectal cancer, which may be an independent risk factor for the occurrence of colorectal cancer.
The mechanism by which Helicobacter pylori increases the risk of colorectal cancer is currently not fully understood.
Some studies speculate that it may be related to the following mechanisms:
Hypergastrinemia caused by Helicobacter pylori infection;
Helicobacter pylori infection leads to atrophic gastritis, causing a decrease in gastric acid secretion, thereby changing the normal gastrointestinal flora.
The relationship between Hp and colorectal tumors is still unclear, but most studies believe that Hp infection plays an important role in the occurrence and development of colorectal polyps and colorectal cancer.
For patients with Hp infection and Hp infection-related gastritis, especially elderly patients with chronic atrophic gastritis, colonoscopy is recommended to screen for colorectal tumors.
At present, the mechanism of the increased risk of colorectal tumors caused by Hp infection is not clear, but hypergastrinemia, high expression of COX-2, and immune tolerance are among the possible mechanisms currently considered, and the specific signaling pathways need to be further studied.
For those who are Hp positive, it is best to do it together with gastrointestinal endoscopy
The incidence of colorectal cancer has gradually increased in China in recent years. The incidence of colorectal cancer in young people is also increasing. Colorectal cancer usually gradually develops from benign colon polyps to malignant tumors, which takes many years. At any stage before the occurrence of cancer, colonic polyps are found through colonoscopy. Generally, the polyps can be removed by endoscopic treatment to avoid the occurrence of malignant tumors.
Colorectal cancer was once a high-incidence tumor in the American population. With the support of the government, the United States has continuously popularized routine colonoscopy screening and included colonoscopy in commercial insurance in recent years, which has led to a decline in the incidence of colorectal cancer in the American population in recent years. Has exceeded 50%.
For those over 35-40 years old who are found to have Helicobacter pylori infection, it is recommended not only to have a gastroscopy, but also a colonoscopy, especially for patients who have developed atrophic gastritis or have a family history of tumors.
(source:internet, reference only)