A study in the journal “Gut” has found a link between the use of antibiotics and the odds of bowel cancer. The results of the study have shown that using antibiotics can increase the chances of bowel cancer in a person. But these can also lead to a reduction in the risk of rectum cancer.
About 70% of the patients with bowel and rectal cancers were previously prescribed with antibiotics
Antibiotics are drugs that can fight bacterial infections. These have a long-lasting impact on the gut microbiota. And it can also alter the balance of harmful and useful bacteria. In 2010, patients took about 70 billion doses of antibiotics.
The level of risk may depend upon the class and type of antibiotic (capsules/pills) used. This pattern of risk can be related to the differences in the activity of gut bacteria along the length of the intestine. And it also implies that one should be careful while prescribing antibiotics.
The site of cancer is also related to the use of antibiotics. The people with cancer in the proximal colon were more prescribed with the antibiotics that target anaerobes in contrast to the patients without cancer. Conversely, the antibiotic use had no association with the cancer of the distal colon.
In this study, the research team has tried to find how antibiotics can affect the risk of bowel and rectal cancer. The team has assessed the data submitted to CPRD in 1989 – 2012. This contains the data from 674 general practices. And it involves the medical records of about 11.3 million people – that is 7% of the population of the UK.
The study has collected the prescriptions of 28,930 patients during a time of 8 years. It includes 19,726 cases of bowel cancer and 9254 cases of rectal cancer. As a control, the team has taken the data of 137,077 patients, without cancer, and matched for sex and age.
The data has shown that the medics have prescribed antibiotics to 70% of the patients with bowel and rectal cancer and to 68.5% of the control patients. And 6 out of 10 patients have received more than one class of antibiotics.
Using antibiotics for more than 16 days can heighten the odds of bowel cancer
The link between bowel cancer and antibiotics use was more evident in patients who were on these drugs for more than 10 years before the cancer diagnosis. This study has also considered many influencing factors, like smoking, moderate to heavy drinking, or excess body weight.
And it has found that the use of antibiotics for more than 16 days can increase the chances of bowel cancer. Where the impact was maximum for the cancers in the proximal colon. In contrast, using antibiotics for more than 60 days has led to a 15% decrease in the odds of rectum cancer.
Later, the research team limited the study to the patients prescribed with only one class of antibiotics. And it has found that penicillin can constantly lead to an increase in the risk of cancer in the proximal colon. In comparison, the decrease in the odds of rectal cancer was related to the intake of tetracyclines.
Overall the study suggests that the use of antibiotics increases the chances of bowel cancer. But this study is purely observational. And it hasn’t allowed the research team to record the hospital treatment or the influencing lifestyle factors for all patients. Whereas these concerns may affect the overall risk of cancer.
Original Source: “https://gut.bmj.com/content/early/2019/07/11/gutjnl-2019-318593”