Antibiotic exposure may increase risk of cancer

The microbiome has been implicated in several cancers including gastrointestinal and breast cancer with many hypotheses proposed as to why bacterial dysbiosis is associated with cancer onset. Recent studies in mice as well as epidemiological studies have provided further evidence that specific bacterial composition led to tumor formation and this could be blocked by antibiotics. In a new study, scientists at the University of Pennsylvania aimed to use epidemiological data to evaluate the association between antibiotics and cancer risk of the skin, lung, breast, gastrointestinal and genitourinary tract. 

The scientists used data from The Health Improvement Network (THIN) database, a medical record database from the United Kingdom containing the information of approximately 11 million individuals. They looked at 15 different malignancies and in order to focus on sporadic cancers, they excluded any individuals with family cancer syndromes as well as any subjects that were diagnosed prior to the age of 20. With every case of cancer, they used four matched controls resulting in 125, 441 cases and 490, 510 controls analyzed for the study.

They found that the use of penicillin resulted in an increased risk of esophageal, gastric, and pancreatic cancers and was 1.4 for gastric cancers associated with greater than 5 courses of antibiotics. Lung cancer risk also increased with penicillin, cephalosporins, or macrolides. Prostate cancer also so a slight increase with several types of antibiotics as well as breast cancer after sulphonamide exposure.

They found for any type of malignancy there was no association between a single course of antibiotic use and increased risk but there was a correlation between greater number of antibiotic courses and cancer risk. Penicillin was associated with the most significant cancer risk while anti-virals, anti-fungals, and tetracylines were not associated with increased risk of cancer. While the increase in incidence was quite small (approximately 20:100,000), it is an important finding that antibiotics may be having a wider impact than previously believe. It is important that future studies look at the mechanisms for how antibiotics are causing this increased cancer risk as well as the effects of age of antibiotic exposure on cancer risk.

Study finds that C-sections are not a risk factor for IBD

Inflammatory bowel disease (IBD) is a disease of the gut made up primarily of two diseases, primarily Crohn's disease and ulcerative colitis. In IBD, the gut and other parts of the digestive tract are attacked by the body's own immune system.  It is not clear how or why IBD occurs but there is a significant amount of research looking at this. It is known that the human gut microbiome goes through a lot of changes from birth through the first few years of life before stabilizing into the “adult” composition. Therefore, looking at the first years of life could be critical for understanding IBD. Researchers in Canada, in a study published by Clinical Gastroenterology and Hepatology, set out to determine if birth by Cesarean section increases likelihood of IBD.

The logic behind this hypothesis is that birth by vaginal delivery would expose the infant to the mother’s vaginal bacteria, which could possibly be essential in the development of the infant’s own microbiome. To study whether C-sections are a risk factor for IBD, the researchers gathered data from the University of Manitoba IBD Epidemiology Database, which keeps health records of all Manitobans diagnosed with IBD between 1984 and March 2010. These records were matched with birth and maternal health records. 1,671 IBD patients were linkable with mothers and therefore used for analysis. 10,488 matched controls were also used.

Analysis showed that IBD patients were no more likely to be born by C-section than the controls. Additionally, urban rather than rural residence was associated with higher instances of IBD. Within families, the likelihood of IBD was not different between C-section and non-C-section siblings.  

In conclusion, there does not appear to be an increased risk for inflammatory bowel disease if a child is born by C-section. Factors such as breastfeeding, socioeconomics, living environment, pets, etc. are still being analyzed for possible contribution to gut microbiome dysbiosis.

Study shows different microbiomes associated with ingesting artificial sweetners

Last year a very important study showed how eating artificial sweeteners could actually increase risk of obesity and diabetes due to a microbiome-mediated response.  Based on this study, researchers from George Mason University investigated the microbiome differences between folks that eat artificial sweeteners, like aspartame and acesulfame-K, and those that do not.  They published their results in the journal Annals of Epidemiology.

The researchers surveyed 31 adults and gave them a questionnaire regarding their eating habits over the previous four days.  Then, on the 5th day the scientists measured the bacteria and the genes those bacteria expressed in each subjects stool.  The scientists learned that the microbiomes did not vary substantially between the two groups, but there were statistically significant differences in the overall diversities of the groups.  In addition, there were no significant differences in the genomes of the bacteria, again suggesting the microbiome is not considerably affected by the ingestion of these sweeteners.  Unfortunately, the authors did not comment on which differences they perceived as being important.

This article suffered from many flaws in its analysis, so we take the results with a grain of salt.  Nonetheless, epidemiological studies in humans like this one are important in supporting the conclusions of studies that demonstrate effects in mice.  The cost/benefits of eating artificial sweeteners versus regular sucrose are still being evaluated, so in the mean time we encourage our readers to eat lots of veggies.