Antibiotic use linked to increased risk of precancerous colon polyps

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Recent evidence suggests that antibiotics, which affect the makeup of intestinal bacteria, might be associated with an increased risk of colorectal cancer. A team led by researchers from Harvard Medical School wanted to see if antibiotic use is also associated with adenomatous polyps, precursors of colon cancer that significantly increase the risk of developing the disease.

The team analyzed data from 16,642 women ages 60 or older participating in the Nurses' Health Study. They first looked at participants' antibiotic use from ages 20 through 59 and in the most recent four years. They also checked the results with the women's colonoscopies and found 1,195 cases of adenomatous polyps.

They found that women who used antibiotics for two months or longer at any time during their 20s and 30s had a 36% greater risk of developing adenomatous polyps compared with women who had not used those medications during those years. For women who used antibiotics for two months or more in their 40s and 50s, the risk was 69% higher than for nonusers. In contrast, antibiotic use within the past four years was not associated with a higher risk of the polyps.

If confirmed by additional studies, the results, published online April 4, 2017, by the journal Gut, suggest another reason to limit the use of antibiotics.