The role of microbiomes in gastrointestinal cancers: new insights Aref Yarahmadi and Hamed Afkhami Gastrointestinal (GI) cancers account for over 33% of new cancer cases globally and pose a significant public health burden. Recent studies indicate a rising trend in GI malignancies over the past 5-10 years, highlighting the need for understanding the role of the microbiome in their development. The gut microbiome, which includes bacteria, viruses, and fungi, plays a crucial role in maintaining health and can influence the progression of GI cancers. Alterations in the composition and abundance of the microbiome have been associated with various GI cancers, including colorectal, gastric, hepatic, and esophageal cancers. The gut microbiome produces short-chain fatty acids (SCFAs) that have beneficial effects on the human body and can influence the efficacy of cancer treatments such as chemotherapy, immunotherapy, and radiotherapy. The microbiome is involved in the development of GI cancers through various mechanisms, including the production of pro-inflammatory cytokines, the activation of cyclooxygenase 2 (COX-2), and the alteration of immune responses. Dysbiosis, or an imbalance in the microbiome, can lead to chronic inflammation and increase the risk of cancer. Certain bacteria, such as Fusobacterium nucleatum, Bacteroides fragilis, Escherichia coli, and Peptostreptococcus anaerobius, have been linked to the development and progression of GI cancers. These bacteria can influence the tumor microenvironment and contribute to treatment resistance. The microbiome also plays a role in the prevention and treatment of GI cancers. Probiotics and fecal microbiota transplantation (FMT) have shown potential in restoring a healthy microbiome and improving outcomes in cancer patients. However, more research is needed to fully understand the complex interactions between the microbiome and GI cancers. The role of the microbiome in various types of GI cancers, including colorectal, gastric, liver, and esophageal cancers, is an area of active research with significant implications for cancer prevention and treatment.The role of microbiomes in gastrointestinal cancers: new insights Aref Yarahmadi and Hamed Afkhami Gastrointestinal (GI) cancers account for over 33% of new cancer cases globally and pose a significant public health burden. Recent studies indicate a rising trend in GI malignancies over the past 5-10 years, highlighting the need for understanding the role of the microbiome in their development. The gut microbiome, which includes bacteria, viruses, and fungi, plays a crucial role in maintaining health and can influence the progression of GI cancers. Alterations in the composition and abundance of the microbiome have been associated with various GI cancers, including colorectal, gastric, hepatic, and esophageal cancers. The gut microbiome produces short-chain fatty acids (SCFAs) that have beneficial effects on the human body and can influence the efficacy of cancer treatments such as chemotherapy, immunotherapy, and radiotherapy. The microbiome is involved in the development of GI cancers through various mechanisms, including the production of pro-inflammatory cytokines, the activation of cyclooxygenase 2 (COX-2), and the alteration of immune responses. Dysbiosis, or an imbalance in the microbiome, can lead to chronic inflammation and increase the risk of cancer. Certain bacteria, such as Fusobacterium nucleatum, Bacteroides fragilis, Escherichia coli, and Peptostreptococcus anaerobius, have been linked to the development and progression of GI cancers. These bacteria can influence the tumor microenvironment and contribute to treatment resistance. The microbiome also plays a role in the prevention and treatment of GI cancers. Probiotics and fecal microbiota transplantation (FMT) have shown potential in restoring a healthy microbiome and improving outcomes in cancer patients. However, more research is needed to fully understand the complex interactions between the microbiome and GI cancers. The role of the microbiome in various types of GI cancers, including colorectal, gastric, liver, and esophageal cancers, is an area of active research with significant implications for cancer prevention and treatment.