Health & Fitness

Colon cancer risk in misuse of antibiotics

Stomach ache
Stomach ache. FILE PHOTO | NMG 

At one point in their lives, most Kenyans have used antibiotics to treat a myriad of infections and diseases caused by bacteria.

Despite their significance in the medical field, health experts are concerned about the increasing cases of antibiotic resistant bacteria caused by the misuse of these drugs.

Already, infectious diseases such as pneumonia, tuberculosis, cholera and blood poisoning have become difficult to manage, claiming the lives of many Kenya.

If the problem persists, health experts are concerned that antibiotic resistance could water down achievements brought about by modern medicine.

This is because doctors usually rely on effective antibiotics to ward off infections during chemotherapy, organ transplants and life-saving surgeries.


As nations mark the Antibiotic Awareness Week (November 18-24), the World Health Organisation is calling for the responsible use of these medicines, with the knowledge that their future depends on all of us.

The UN health agency has urged people to only use antibiotics when prescribed by a certified health professional. Over the counter medicines are strictly prohibited. In addition, recommended doses should be adhered to, even if people feel like their health has improved.

Aside from just preventing antibiotic resistance, the judicious use of the drugs also offer cancer prevention benefits to human beings.

A new study published in the Gut Journal shows that the misuse use of antibiotics enhances colon cancer risk.

According to the authors, the most likely explanation for the high cancer risk is the radical change that antibiotics wreak on the bacteria that live in the intestines.

During the study, researchers from the Johns Hopkins Kimmel Cancer Centre did an extensive analysis of medical records for more than 11 million patients in the United Kingdom.

This included data on antibiotics drug prescription and colon cancer diagnoses.

The individuals were compared with other healthy patients that never developed the disease despite having similar characteristics as them (like age, gender and where their general practitioner was located).

After a 23-year period (from 1989 to 2012), the results showed that the people who developed colon cancer were slightly more likely to have been exposed to antibiotics than those that did not.

Further investigations showed that antibiotic exposure was associated with 15 percent increased risk for cancer in the proximal colon (the first and middle parts of the colon) but not the distal colon (last part of the colon).

And this risk happened particularly after exposure to classes of antibiotics that kill anaerobic bacteria, such as those in the penicillin family.

Anaerobic bacteria are organisms that do not require oxygen for growth. In humans, these bacteria are most commonly found in the gastrointestinal tract. They play a role in conditions such as appendicitis, diverticulitis (inflamed pouches in the lining of your intestine) and perforation of the bowel.

Among the compelling findings, the researchers say, was the rapid onset of increased colon cancer risk at eight percent after only 15 to 30 days of total antibiotic exposure, and 15 percent enhanced risk with 30 or more days of using the drugs.

Cancers that developed in the colon were linked with antibiotic exposure for about a decade. There was no increased risk with exposures less than 10 years.

Based on these findings, the researchers call for the judicious use of antibiotics, which are often improperly used or overprescribed.

"The primary message of this study is the importance of antibiotic stewardship: not treating common viral infections with antibiotics, taking the drugs for the shortest time period possible, and using targeted antibiotics rather than broad spectrum ones," said Dr Cynthia Sears, the lead author of the study and professor of cancer Immunotherapy at the Johns Hopkins Kimmel Cancer Centre.

"This research adds to our understanding that these drugs can have significant off-target effects, including the induction of chronic illnesses."

Although antibiotics are most often highly effective at eradicating bacterial infections, Dr Sears explains that they can also change the balance of bacteria in the gut by killing beneficial ones and allowing the bad ones to thrive.

Some of these surviving bacteria could be carcinogenic. They can thus encourage the growth of polyps (lumps) that develop into malignant or cancerous tumours.

Sometimes, people try to address the challenge by consuming probiotic-rich foods or supplements that encourage the growth of good or helpful bacteria in the gut.

These foods may include natural yoghurt (devoid of artificial sweeteners, sugars and flavourings), traditional buttermilk (must not be cultured) and aged cheese (such as cheddar, gouda, or mozzarella).

Despite their benefits, health experts note that rather than trying to add beneficial bacteria back to the intestines, a better way to avoid potentially increased colon cancer risk from antibiotic use is through more cautious prescribing of the drugs.