Human microbiota is the set of symbiotic microorganisms that coexist with the human organism without damaging it. Human microbiota is a good example of mutualism: cooperation between different types of organisms that brings an advantage to each of them. By “microbiota” we mean the set of actual microorganisms, while the term “microbiome” refers to the genetic heritage of the microbiota. The so-called “intestinal flora” is part of the complex human microbiota. An important function of human microbiota is the breakdown of substances that our system is unable to dismantle, such as cartilage and cellulose molecules. Another important function is the synthesis of indispensable substances, for example vitamin K, which plays an essential role in blood clotting. Human microbiota competes with non-symbiotic bacteria that could replicate in various areas of the body. By “vaginal flora” or “vaginal bacterial flora” we mean the set of microorganisms, mostly of bacterial origin, which colonize the vaginal cavity, and which constitute a form of defense against pathogenic attackers. The quantity and type of bacteria present in the flora has a direct influence on the state of a woman’s health. A healthy vaginal flora helps prevent fungal infections (typically candida, the cause of vaginal candidiasis) and other possible pathologies, occupying the resources necessary for their development and metabolism. Flora imbalances can also be caused by hormonal imbalances or disorders, by physical or psychological stress but also by excessive intimate hygiene with unsuitable or too aggressive products. Pathologies connected to microbiota are still the subject of study today, but numerous publications show that an altered composition of microbiota is implicated in psychiatric pathologies (for example, among the most studied we find anxiety disorder), in chronic inflammatory diseases, heart failure, and also in cancer. The aim of this review is to emphasize the importance of microbiota on the incidence, evolution, prevention and treatment of gynecological and breast cancers. We aim to clarify the existence of various “local” microbiota, their close relationship with intestinal microbiota and metabolic conditions connected to it. Also, their impact on oncological pathology, and the real possibility of modulating it (therefore, interfering with oncological history of the patients) through targeted but common clinical practice therapeutic interventions, such as the use of phytotherapeutic compounds, nutraceuticals, probiotics and prebiotics. The intent of this work is, on one hand, to highlight the benefits of a correct diet in prevention and treatment of gynecological neoplasms, on the other hand, to highlight false information, which can cause harm to patients’ health.