Zinc is a vital nutrient for human health. Over 300 biological functions in the human body rely on zinc. Even though zinc is incredibly important for our physiology and pathology, our current understanding of zinc, as it relates to tumor cell biology, leaves much to be desired. As with other natural, nonpatentable, and inexpensive agents, zinc remains a subject of explorative research for scientific interest rather than being promoted for practical use. To date, more than 5000 studies with the keywords 'zinc' and 'cancer' have been indexed in the Web of Knowledge portal. Although the numbers of papers have increased 2.5-fold during the last decade, these vast research data have not generated a single recommendation for the incorporation of zinc use in cancer prevention and treatment. In this review, we intend to analyze the current available research data and epidemiological and clinical evidence on the role of zinc in human cancer prevention and treatment. We focus on the cancers - prostate, breast, and pancreatic - for which the most basic and epidemiological studies with zinc have been carried out. The pancreas, and prostate and mammary glands are secretory tissues that have unusual zinc requirements; they tightly regulate zinc metabolism through integration of zinc import, sequestration, and export mechanisms. This suggests to us that zinc could play an important role in the physiology and pathology of these organs. The objective of this review was to stimulate more interest in the research field, focusing on the role of zinc as a possible preventive and therapeutic agent and the accelerated application of this inexpensive and easily accessible nutrient in clinical oncology. Copyright (C) 2016 Wolters Kluwer Health, Inc. All rights reserved.