Zinc (Zn) is a trace element crucial for oxidative stress, apoptosis, the immune response, and more globally for various processes involved in cellular homeostasis. In some cancers, Zn homeostasis is dysregulated. In this review, the role of Zn in cancer and all the components associated to Zn, the use of Zn and Zn -related proteins as biomarkers and Zn-based strategies for the treatment of tumors will be described. ZIP and ZnT are proteins related to Zn metabolism in normal conditions. In cancer, the level of expression of Zn related proteins is abnormal. These Zn proteins may act as prognostic or diagnostic biomarkers, and may be helpful for detecting early-stage cancers or monitoring the course of the disease. Additionally, Zn and its pathways may also be targeted to treat cancers. Indeed, the use of metals for binding Zn cations allows to regulate the biodistribution of Zn within cells, and will control several downstream signaling pathways. Zinc may also be directly used as a therapeutic substance to improve the prognosis of cancer patients, especially with the supplementation of zinc or the use of Zn oxide nanoparticles.