Long-term antibiotic use in early to mid-life linked to cancer-inducing polyps

April 4, 2017

Long term antibiotic use in early to mid life may be linked to a heightened risk of abnormal growths in the colon and rectum—known as polyps or colorectal adenomas—which precede the development of most cases of bowel cancer, reveals research published online in the journal Gut.

The findings add to emerging evidence that the type and diversity of bacteria in the gut, referred to as the 'microbiome,' may have a key role in the development of cancer, say the researchers.

Previous research has indicated that exposure to antibiotics may be associated with a heightened risk of developing , but these studies have involved relatively short monitoring periods, so undermining the strength of the associations found. And the potential association with polyp risk has not been explored.

To try and get round these issues, the research team drew on data from the Nurses Health Study. This has been monitoring the health of 121,700 US nurses who were all aged between 30 and 55 when they entered the study in 1976.Since joining, study participants have filled in detailed questionnaires every two years on demographics, lifestyle factors, medical history and disease development, and every four years on their dietary habits.

For the purposes of the current study, analysis of the data was restricted to 16,642 women who were aged 60 and older in 2004, able to provide a history of antibiotic use between the ages of 20 and 59, and who had had at least one bowel investigation (colonoscopy) between 2004 and 2010.

During this period, 1195 adenomas were newly diagnosed in this group.

Recent use of antibiotics within the past four years wasn't associated with a heightened risk of an adenoma diagnosis, but long term use in the past was.

Compared with those who hadn't taken antibiotics for any extended period in their 20s and 30s, those who had taken them for two months or more were 36% more likely to be diagnosed with an adenoma.

This association held true irrespective of whether the adenoma was considered high or low risk for bowel cancer, but was stronger for growths located in the proximal, rather than the distal, colon.

The proximal colon refers to the caecum (pouch at the junction of the small and large intestines), ascending colon, hepatic flexure (the sharp bend between the ascending and transverse colon), transverse colon, and the splenic flexure (the sharp bend between the transverse colon and descending colon). The distal colon refers to the descending or sigmoid colon.

Similarly, women who had taken antibiotics for two months or more during their 40s and 50s were 69% more likely to be diagnosed with an adenoma than those who hadn't taken these drugs for any extended period.

Once again, this association held true, irrespective of whether the adenoma was high or low risk for bowel cancer, and was more strongly linked to proximal colon adenomas.

And compared with women who had not been on antibiotics for any length of time from their 20s to their 50s, those who had taken these drugs for more than 15 days between the ages of 20 and 39, and between the ages of 40 and 59, were 73% more likely to be diagnosed with an .

This is an observational study so no firm conclusions can be drawn about cause and effect, added to which the researchers didn't gather information on the type or formulation of antibiotic taken, and some adenomas might have been present before antibiotics were used.

Nevertheless, there is a plausible biological explanation for the associations found, they suggest.

Antibiotics fundamentally alter the gut microbiome, by curbing the diversity and number of bacteria, and reducing resistance to 'hostile' bugs, they say. Previous research points to depletion of certain types of bacteria and an abundance of others in patients with bowel cancer.

This might all have a crucial role the development of bowel cancer, added to which the bugs that require antibiotics may induce inflammation, which is a known risk for the development of bowel , say the researchers.

"The findings, if confirmed by other studies, suggest the potential need to limit the use of and sources of inflammation that may drive tumour formation," conclude the researchers.

Explore further: Family history of colon cancer calls for earlier screening

More information: Long term use of antibiotics and risk of colorectal adenoma, DOI: 10.1136/gutjnl-2016-313413

Related Stories

Family history of colon cancer calls for earlier screening

March 21, 2017
(HealthDay)—If you've got a family history of colon or rectal cancers, you probably need to start screening for these conditions before you turn 50, a cancer expert says.

Certain types of polyps may warrant keeping closer tabs on the colon

April 13, 2016
Being on the lookout for certain features of polyps may help physicians keep a closer eye on patients at risk for colorectal cancer.

Technology advances help to prevent, lessen impact of colon cancer

March 14, 2017
Approximately 140,000 people are diagnosed with colorectal cancer in the U.S. each year. March is Colorectal Cancer Awareness Month.

Keep colon cancer at bay

March 22, 2017
(HealthDay)—Colon cancer can be treated and cured if it's diagnosed early, and a colonoscopy is one of the best ways to detect the disease, a gastroenterologist says.

Exercise cuts bowel cancer risk

January 4, 2012
Researchers at the University of Western Australia (UWA) and the Western Australian Institute for Medical Research (WAIMR) have found people who engage in vigorous physical activity may be protected against types of colorectal ...

Poor colonoscopy prep hides pre-cancerous polyps

March 27, 2012
(Medical Xpress) -- What happens on the day before a colonoscopy may be just as important as the colon-screening test itself.

Recommended for you

Scientists pinpoint gene to blame for poorer survival rate in early-onset breast cancer patients

December 15, 2017
A new study led by scientists at the University of Southampton has found that inherited variation in a particular gene may be to blame for the lower survival rate of patients diagnosed with early-onset breast cancer.

'Bet hedging' explains the efficacy of many combination cancer therapies

December 14, 2017
The efficacy of many FDA-approved cancer drug combinations is not due to synergistic interactions between drugs, but rather to a form of "bet hedging," according to a new study published by Harvard Medical School researchers ...

Liquid biopsy results differed substantially between two providers

December 14, 2017
Two Johns Hopkins prostate cancer researchers found significant disparities when they submitted identical patient samples to two different commercial liquid biopsy providers. Liquid biopsy is a new and noninvasive alternative ...

Testing the accuracy of FDA-approved and lab-developed cancer genetics tests

December 14, 2017
Cancer molecular testing can drive clinical decision making and help a clinician determine if a patient is a good candidate for a targeted therapeutic drug. Clinical tests for common cancer causing-mutations in the genes ...

Newest data links inflammation to chemo-brain

December 14, 2017
Inflammation in the blood plays a key role in "chemo-brain," according to a published pilot study that provides evidence for what scientists have long believed.

Scientists unlock structure of mTOR, a key cancer cell signaling protein

December 14, 2017
Researchers in the Sloan Kettering Institute have solved the structure of an important signaling molecule in cancer cells. They used a new technology called cryo-EM to visualize the structure in three dimensions. The detailed ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.