Recent scientific research has indicated that the gut microbiota constitutes a nuanced, diverse ecosystem of microorganisms that have gained significant attention due to its crucial involvement in shaping human health and diseases. In particular, the gut microbiota plays a pivotal role in cancer prevention, and disturbances in its composition and function, known as dysbiosis, that have been linked to an increased risk of developing various malignancies. The gut microbiota exerts a myriad of effects on the production of anti-cancer compounds, the host?s immune system and inflammation, underscoring its crucial involvement in cancer. Additionally, recent studies have shown that the gut microbiota has a role in the development of cancer, influencing cancer risk, co-infections, disease progression, and treatment response. The observation of reduced efficacy of immunotherapy in patients receiving antibiotic treatment indicates a substantial influence of the microbiota in mediating the toxicity and response of cancer therapy, notably immunotherapy, and its immune-related side effects. A growing body of research has focused on cancer treatments that target the microbiome, including probiotics, dietary modifications, and faecal microbiota transplantation (FMT). The forthcoming era of personalised cancer therapies is anticipated to prioritise tumor evolution, molecular and phenotypic heterogeneity, and immunological profiling, with gut microbiota assuming a pivotal position in this domain. This review aims to offer clinicians a comprehensive perspective on the microbiota-cancer axis, including its influence on cancer prevention and therapy and highlights the importance of integrating microbiome science into the design and implementation of cancer therapies.  Kulcsszavak: gut microbiota, cancer, prevention of cancer, ICI therapies, probiotics, faecal microbiota transplantation, cancer treatment