Several malignant disorders of human tissues affect a large proportion of people in Colombia and worldwide, which has led to an increase in pharmacological treatments for these diseases, without the real benefit being clear to the patients who receive them. Furthermore, there are doubts about the quality of the evidence on which the institutions that support anticancer treatments with medications are based, such as the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). Our objective was to know how efficacy studies are carried out and how treatments with medications offered to people with cancer are approved. A narrative review was carried out, which was based on the formulation of questions that guided the development of the topics that were included. The search strategy was done in PubMed in a structured but non-systematic way. Articles published in english and spanish were included, without restriction by publication date.