Blacks at Greater Risk of Precancerous Colon Polyps
TUESDAY, Sept. 23 -- Black people undergoing colon cancer screening are more likely to have large precancerous polyps than are whites.
Black men had a 16 percent increased risk of polyps more than 9 millimeters (mm) in size than white men. And the difference in women was even more striking with black women having 62 percent higher odds of a 9 mm or larger polyp, according to new research.
"We've known for a long time that colon cancer is more common in blacks than in whites, and that blacks are more likely to die from colon cancer than whites," said the study's lead author, Dr. David A. Lieberman, a professor of medicine and chief of gastroenterology at Oregon Health and Science University in Portland.
"Previous studies have suggested these differences may be from a lack of access to health care, or a failure of doctors to recommend screening, or a failure of the patients to follow through on screening. But, since we took a look at patients who were already getting screening exams, access and adherence weren't an issue, and we found that black men and women had more serious polyps," Lieberman said.
The good news, he added, is that "many colon cancers can be prevented with screening," and this study shows that blacks may stand to benefit even more from colon cancer screening than whites.
Results of the study were published in the Sept. 24 issue of the Journal of the American Medical Association.
The death rates for colon cancer are about 40 percent higher in blacks than in whites, according to background information in the study. And, the disease incidence rate is between 15 percent and 23 percent higher for blacks.
The new study included 5,464 blacks and 80,061 whites who had undergone screening colonoscopy in 67 different centers across the United States. Of that group, the researchers found 422 blacks (7.7 percent) had one or more polyps that were larger than 9 mm. Among whites, almost 5,000 (6.2 percent) had one or more polyps of that size. Removing large colon polyps is important, because they are likely to turn into colon cancer.
The researchers also found that the differences persisted across different age groups. And, black women had a "strikingly" higher incidence of polyps, according to Lieberman.
"This study confirms the possibility that genetic and biological factors are playing a role in colon cancer," said Lieberman.
But, not everyone's convinced by these findings.
Dr. Otis Brawley, chief medical officer at the American Cancer Society, said the study didn't control, or compensate, for previous screening tests or socioeconomic status of the participants -- two factors he said could seriously influence the study's conclusions.
"Black women in the U.S. are more likely to have [a particular type of breast cancer called] triple-negative breast cancer than white women, and many experts have written about it and wondered if it's biology. But, if you go to Scotland, where there are few blacks, researchers wonder why poor white women are more likely to have triple-negative breast cancer," said Brawley, who added, "We tend to let our racial lens interfere with being scientific."
"It may be that colon cancer is more aggressive in blacks than in whites," he said, but the issue definitely needs more study.
No matter what your color, one thing both experts agree on is the need to have colon cancer screening beginning at age 50 for those with an average risk of the disease.
"With colon cancer screening, we have the unique opportunity to actually prevent cancer," Lieberman said.
To learn more about colon cancer screening, visit the American Academy of Family Physician's FamilyDoctor Web site.
Posted: September 2008
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