مقالات پذیرفته شده در هشتمین کنگره بین المللی زیست پزشکی
Impact of Long-Term Antibiotic Use on Gut Microbiota and Its Implications for Colorectal Cancer Risk
Impact of Long-Term Antibiotic Use on Gut Microbiota and Its Implications for Colorectal Cancer Risk
Forough Perota Ghalati,1Zahra Gholizadeh farshi,2,*
1. Department of Cellular and Molecular Biology and Biochemistry, School of agriculture, Islamic Azad University Shiraz branch, Shiraz, Iran 2. Department of Pathobiology, School of Veterinary Medicine, Shiraz University, Shiraz, Iran
Introduction: In terms of cancer incidence, colorectal cancer (CRC) is the second most frequent cancer in women, after breast cancer, and the third most common cancer in men, after prostate and lung cancer. It represents 55% of CRC cases in developed regions, with Central and Eastern Europe having the highest mortality rates. Moreover, it is a multifactorial disease with an unclear primary cause. However, extensive epidemiological research has identified several risk factors, including genetic predisposition, colorectal polyps, inflammatory bowel disease, smoking, alcohol consumption, and long-term, repeated, or combined antibiotic use. Additionally, gut microbiota dysbiosis has been recognized as a potential risk factor for CRC. The purpose of this study is to examine the relationship between the frequent use of antibiotics and its effect on the intestinal microbiota and the occurrence of colorectal cancer.
Methods: The human microbiota consists of approximately 500-1000, distinct species of bacterial cells. The significance of this entity resides in its capacity to provide defense against pathogens, facilitate the metabolic breakdown of polysaccharides, facilitate the biosynthesis of vital vitamins, and serve a critical role in the preservation and regulation of the immune system. The gut microbiome significantly contributes to overall health maintenance and disease prevention. Also, the human intestinal tract, a nutrient-rich environment, hosts the largest microbial communities. The gut microbiota is gaining significant attention due to its influence on CRC risk through metabolites and immune interactions. Certain bacteria that produce hydrogen sulfide, acetaldehyde, and secondary bile acids can increase CRC risk. For example, the human gut microbiota functions as an essential “organ,” contributing to nourishment, regulating epithelial development, and modulating immunity. Researchers are investigating the differences in gut microbiota between CRC patients and healthy individuals, aiming to identify reliable microbial markers for CRC precursors.
Results: Accumulating evidence suggests that long-term, frequent, or combined antibiotic use can also be a risk factor for CRC. The worldwide use of antibiotics is projected to increase significantly. The use of antibiotics, even narrow-spectrum antibiotics, has solid and stable effects on the structure of the intestinal microbiota, changes the composition, and reduces the diversity of the human microbiota. Antibiotics allow colonization of pathogenic microbes and may allow colonization with carcinogenic bacteria that cause local inflammation and tumor formation. Previous epidemiological studies in humans have evaluated the possible effect of antibiotic exposure on cancer risk in the lung, breast, prostate, colon, and skin with conflicting results. In this regard, antibiotics may be of interest because their use may seriously affect the diversity of the colonic microbiota. The administration of antibiotics has been linked to a heightened susceptibility to CRC.
Conclusion: As a result, several risk factors influence the development of CRC, with dysbiosis gut microbiota and antibiotics being particularly significant. The widespread use of antibiotics globally profoundly impacts our gut microbiota, leading to microbiome dysbiosis. Given the indispensable role of the intestinal microbiota in human health, modifications in their arrangement and composition can establish an environment conducive to the proliferation of specific pathogenic bacteria, which are known to contribute significantly to the development of colon tumors.