- Antibiotics have been in
use for treatment against harmful infectious bacteria; however, apart from
killing the infectious agent they also kill the normal microflora of the
- 69% higher risk of adenomas was identified among
women who took antibiotics for longer than two months during their 40s and 50s
when compared with women who were not on antibiotics.
increased risk for adenomas was identified among women who were on antibiotics
for longer than 15 days, at least twice during mid-life
There is an increased
risk for abnormal growth in the colon as well as the rectum, on prolonged use
of antibiotics during mid-life, according to a new study. Such growth, known as
or polyps, usually
precedes bowel cancer. The study published in the journal Gut
details the significance of bacteria present in the gut and
their role in the development of cancer.
When the use of
antibiotics was studied in previous research work, it was found to be
associated with an increased risk of developing bowel cancer. However, the
follow-up period has been largely restricted to these studies, which limits the
strength of these studies, and such studies have also not detailed the
association between antibiotic use with the development of polyps.
‘Long-term use of antibiotics kill normal bacteria in the gut which results in the growth of harmful bacteria that in turn increase the risk for polyps.’
between Antibiotic Use and the Development of Polyps
The current study was
based on the information available in the Nurses' Health Study which includes
US nurses aged
between 30 and 55 at the time of the start of the study in 1976. The nurses
were made to fill in the questionnaire, which included questions on lifestyle
factors, demographics, disease, medical history, every two years. The dietary
habits of the nurses were recorded every four years.
The study included
details of 16,642
women who were
able to fill in details about the history of their antibiotic use and who were
aged 60 and above in 2004. Women between 20 and 60 years of age were included
If they had had a bowel investigation at some point in their life.
The findings of the
were identified newly in this groupThe use of antibiotics within the recent 4 years did not affect the risk
for adenomasThere was increased risk for adenomas when
there was long-term use of antibiotics.
There was 36%
increased risk for adenomas when antibiotics were taken for two months or more
when the study participants were in their 20s
or 30s when compared to women who hadn't. The risk of
adenomas was high, irrespective of whether the adenoma had a high or low risk
of developing into bowel cancer. There was a strong
association with growth present in the proximal region (which is the cecum or
the pouch like region present in between the small and the large intestine,
splenic flexure, which refers to the bend that occurs between transverse colon
and the descending colon and the hepatic flexure) rather than in the colon's
distal region, which is the sigmoid colon or the descending colon.
There was 69%
higher risk of adenomas among women who were on antibiotics for two months or
longer when they were in their 40s and
50s, compared to women who were not on antibiotics during that stage.
There was 73%
increased risk for adenomas among women who took antibiotics for more than 15
days between the ages of
The scientists caution
that this study was observational and that some adenomas could have been
present even before antibiotic use. However, the existence of the association
between antibiotics and the risk of polyps is plausible, according to the
in the Gut Microbiome by Antibiotics
micro-organisms, irrespective of whether they are pathogenic or part of the
microbiome of the body. The use of antibiotics for a prolonged period of time,
drastically lowers the diversity as well as the number of bacteria. The
reduction in the number of bacteria which are a part of the microbiome could make
way for the colonization of harmful bacteria. This could contribute to the
increased risk for bowel cancer.
A similar study
conducted to identify the risk for developing lung, breast and colon cancer and
the use of antibiotics was carried out as a large observational study
, published in the International Journal
of Cancer. The study found that there was a risk for less common forms of
cancer, including bladder, kidney, male genitals, pancreas, kidney, thyroid
, leukemia and myeloma, with a 1.5 times higher risk
among people who were on six or more antibiotic prescriptions when compared
with people who did not have antibiotics.
The findings of the
study suggest that there is a need to restrict the use of antibiotics as well
as to lower the risk for inflammation that could lead to potentially dangerous
is a Colon Polyp?
A small growth develops
along the inner lining of the large intestine which has an increased risk of
developing into cancer. These small growths or polyps may be present all over
the colon and could vary in size, from several centimeters to a few
These polyps could have
a raised appearance or they could be flat. The raised polyps have a stalk and
resemble the appearance of a cauliflower or a mushroom.
- Yin Cao et.al., 'Long-term use of antibiotics and
risk of colorectal adenoma' BMJ Journal, (2017); Colon Polyps -