In-vivo Studies conducted following the success In-vitro and Dissemination of Anticancer Clinical Trials

Since the beginnings of cancer research, phytochemicals have been a focal point because they were some of the first antineoplastic drugs found (e.g., leucovorin in 1950, carzinophilin in 1954, vincristine in 1963, actinomycin D in 1964, etc.). Additionally, their research is still ongoing today. It is crucial to note that natural substances are used both as adjuvants and chemotherapeutic agents in the treatment of cancer. By summarizing the three aspects of natural compounds' anticancer activity, this review offers a fresh perspective on their use in the field of oncology. Chemotherapeutic drugs because of their inherent antitumor effects, chemopreventive drugs, and sensitizers for multi-drug resistance are the first three categories. Numerous active agents are undergoing preclinical and clinical trials right now. It is crucial to draw attention to the important advancements that have been made in this field of study, with some secondary plant metabolites already in use in medicine and others being tested in human clinical trials as anticancer agents. Phytochemicals have numerous positive effects on human health and are crucial in preventing the development and spread of cancer. Through a diet high in fruits and vegetables, as well as with the aid of highly-standardized supplements containing the active compounds, one may achieve the ideal intake of natural chemopreventive agents.