Extended antibiotic use ups risk of colorectal polyps

Last Updated: 2017-04-05

By Megan Brooks

NEW YORK (Reuters Health) – Long-term use of antibiotics in early and middle adulthood increases the risk of colorectal adenoma, a precursor to colorectal cancer, according to new observational data.

“This study provides additional evidence that the body's normal intestinal bacteria may play a role in maintaining health and disrupting the normal bowel bacteria may be harmful and have some long-term health outcomes including the possibility of developing colon polyps,” Dr. Andrew T. Chan, of the Clinical and Translational Epidemiology Unit at Massachusetts General Hospital in Boston, noted in an interview with Reuters Health.

“The findings suggest that we should be cautious about how we think about our normal bowel bacteria and how we think about whether to do things that disrupt that normal pattern,” said Dr. Chan.

The researchers examined the association between antibiotic use between ages 20 and 39 and ages 40 and 59 (assessed in 2004) as well as recent antibiotic use (assessed in 2008) with risk of subsequent colorectal adenoma, in 16,642 women aged 60 and older enrolled in the Nurses’ Health Study.

All of the women had at least one colonoscopy between 2004 and 2010, and a total of 1,195 incident adenomas were detected.

Increasing total exposure to antibiotics at ages 20 to 39 was significantly associated with a higher risk of colorectal adenoma, the researchers report online April 4 in Gut.

Compared with no antibiotic use, women who used antibiotics for two or more months in their 20s and 30s were 36% more likely to have an adenoma (multivariable odds ratio, 1.36; 95% CI 1.03 to 1.79, P for trend=0.002).

Extended use of antibiotics between ages 40 and 59 was also associated with an increased risk of colorectal adenoma (multivariable OR 1.69; 95% CI 1.24 to 2.31).

The associations were similar for low-risk versus high-risk adenomas (size 1 cm or larger, or with tubulovillous/villous histology, or 3 or more detected lesions), but appeared modestly stronger for proximal compared with distal adenomas.

In contrast, recent use of antibiotics (within the past four years) was not associated with risk of adenoma detection.

Dr. Chan and colleagues say their findings support prior studies of antibiotics and risk of colorectal cancer and extend the findings by demonstrating an association of antibiotics with colorectal adenoma.

“These data provide additional support for the association of antibiotics with colorectal cancer and the potential mediating role of the gut microbiome in carcinogenesis,” they write.

“The findings, if confirmed by other studies, suggest the potential need to limit the use of antibiotics and sources of inflammation that may drive tumor formation,” they add.

The study had no commercial funding and the authors have disclosed no conflicts of interest.

SOURCE: http://bit.ly/2nXyvsF

Gut 2017.