Naeem Nikpour
1 
, Seyed Amir Banikarim
2 , Ahmadreza Maghsoudi
3 , Simin Zeinadini
4 , Zahed Karimi
5 , Roya Raeisi Jaski
6 , Setare Sadeghi
7 , Zahra Eydizadeh
8 , Parzhin Khazdoozi
9* 1 Department of Hematology and Medical Oncology, Faculty of Medicine, Kerman University of Medical Sciences, Kerman, Iran
2 Hematology-Oncology Department, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
3 Department of Internal Medicine, School of Medicine, Isfahan University of Medical Sciences, Isfahan, Iran
4 Student Research Committee, Faculty of Nursing and Midwifery, Isfahan University of Medical Sciences, Isfahan, Iran
5 Department of Internal Medicine, School of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
6 Department of Anesthesia Nursing, Mother and Child Welfare Research Center, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
7 Department of Operating Room, Faculty of Nursing and Midwifery, Community of Health Research Center, Isf.C., Islamic Azad University, Isfahan, Iran
8 Department of Operating Room Nursing, Faculty of Nursing and Midwifery, Hormozgan University of Medical Sciences, Bandar Abbas, Iran
9 School of Nursing, Gerash University of Medical Sciences, Gerash, Iran
Abstract
The gut microbiome significantly influences cancer pathogenesis, progression, and treatment outcomes. Dysbiosis, an imbalance in gut microbial communities, can lead to tumorigenesis and is implicated in approximately 20% of all cancers. The gut microbiota contributes to cancer development through various mechanisms, including inducing chronic inflammation, producing genotoxic metabolites, and modulating signaling pathways. Numerous studies found that, Helicobacter pylori is a known microbial risk factor for gastric cancer. In esophageal cancer, accumulating evidence suggests a crucial role for gut microbiota in its development and progression. Specific microbes like Fusobacterium nucleatum can contribute to aggressive tumor behavior in esophageal squamous cell carcinoma by activating chemokines. Similarly, in colorectal cancer, distinct metagenomic and metabolomic shifts, including an abundance of F. nucleatum, have been identified across various stages of pathogenesis. Beyond pathogenesis, the gut microbiome also affects cancer therapies, particularly immune checkpoint inhibition (ICI). Studies have shown that gut microbiota composition and diversity can predict ICI responses. For instance, certain microbial species like Bifidobacterium spp., have been linked to improved efficacy of anti-PD-L1 antibodies in murine models. The microbiome can also influence the efficacy and toxicity of chemotherapy. Consequently, manipulating the gut microbiome through approaches such as dietary modification, probiotics, and fecal microbiota transplantation is being explored as a potential therapeutic strategy. Fecal microbiota transplantation has shown promise in modulating immune cell infiltrates and gene expression profiles in melanoma patients receiving immune checkpoint inhibitors.