SATURDAY, October 13, 2018 – The same type of bacteria that causes stomach cancer may also increase colon cancer risk, especially among black Americans, a new study finds.
Researchers analyzed data from more than 4,000 colon or rectal cancer cases in the United States. They found a significant association between the rates of these cancers and infection with a virulent strain of H. pylori bacteria, which is particularly prevalent in black Americans.
However, the results do not prove that H. pylori causes colon or rectal cancer. Further investigations are required, noted the authors of the study.
"The link between infection and cancer is intriguing, especially if we can eradicate it with a simple round of antibiotics," said lead author Meira Epplein, cancer epidemiologist at the Duke Cancer Institute.
"Our study provides strong evidence that we need to continue this research to get a definitive cause-effect," added Epplein in a Duke University press release.
The researchers found that antibodies that indicate H. pylori infection were equally common in patients with colorectal cancer and people without cancer – four out of ten patients were positive.
However, there were significant differences between races.
White patients had below-average H pylori infection rates, Asian Americans had average rates, while blacks and Hispanics had high rates. Among blacks, rates were 71 percent in patients with colorectal cancer and 65 percent in non-cancer patients. Among Hispanics, rates were 74 percent for cancer patients and 77 percent for cancer patients.
In studying antibodies to four H. pylori proteins, researchers found that one protein, VacA, was the most associated with an increased risk of colorectal cancer in black Americans. High levels of antibodies to this protein have been associated with colorectal cancer rates in blacks and Asian Americans.
"It was surprising to see that VacA antibody increases the likelihood of colon cancer in African Americans and Asian Americans, and not in whites and Latinos," said Epplein. "This is a big question – are humans different genes based on genetic origin or inheritance? This is part of what we need to find out."
Further studies may show whether antibodies to the VacA protein could serve as a marker for colorectal cancer risk, even if it does not cause the cancer directly, said Epplein.
The results were published online October 5 in the journal Gastroenterology.
The American Cancer Society has more on colon cancer.
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