The human microbiome, consisting of trillions of microbes living in and on the body, plays a significant role in maintaining health and influencing disease development, including cancer. Recent studies have shown that the gut microbiota can modulate the immune system, influence inflammation, and affect the success of cancer treatments. Dysbiosis, or an imbalance in the microbiome, has been linked to several types of cancer, including colorectal and gastric cancer. Researchers are now investigating how restoring a healthy microbiome through dietary changes, probiotics, or other interventions could enhance cancer treatment and prevention. Modulating the microbiome offers a promising new strategy for improving cancer outcomes by enhancing immune responses and making tumors more susceptible to therapy.