Background: Cancer is a disease characterized by uncontrolled cell growth and proliferation. It has become a major health problem in the past decades and is now the second leading cause of death globally. Although, there are different types of treatment such as chemotherapy, immune therapy, radiation, hormone therapy and targeted therapy used against cancer, they have possible side effects and significant deficiencies. Methods: This review aims to outline the benefits of medicinal plants and plant-derived products and highlight why they should be used as novel anti-cancer therapeutics. Electronic databases, including PubMed, Scopus. ScienceDirect, Cochrane library, and MedlinePlus were searched to summarize in vitro, in vivo and clinical studies on anticancer effects of medicinal plants and their bioactive compounds up-to-date. Results: In recent years, a number of medicinal plants have been administered to cancer patients in order to prevent and treat cancer as an alternative therapy. These plants were used because of their rich anticarcinogenic and chemoprotective potentials. In addition to these remarkable properties, these plants have less toxic anticancer, anti-tumor and anti-proliferation agents than traditional therapeutics. Nevertheless, only a small number of natural anti-tumor products including vinblastine, vincristine, podophyllotoxin, paclitaxel (Taxol) and camptothecin have been tested clinically, while vinflunine ditartrate, anhydrovinblastine, NK-611, tafluposide, paclitaxel poliglumex, combretastatins, salvicine, curcumin, indirubin, triptolide, homohaningtonine are still on trial. Conclusion: Consequently, more effective anticancer compounds are identified during the clinical trials; these natural products could be a key source of antitumor agents in modem anticancer therapy. It is expected that novel anticancer phytopharmaceuticals produced from medicinal plants could be effectively used in prevention and therapy for the cancers.
