Cytotoxic/tumor suppressor role of zinc for the treatment of cancer: an enigma and an opportunity.

A major issue relating to many cancers is the absence of effective chemotherapeutic agents; so that most often untreatable morbidity and death are prevalent once the cancer has been detected and has advanced. The search for efficacious anticancer agents is imperative. One potential agent is zinc, which is decreased in the development of some cancers in order to avoid its cytotoxic/tumor suppressor effects on the malignant cells. This provides the basis and opportunity to employ a treatment regimen that restores elevated zinc levels in the malignant cells and elicits the cytotoxic/tumor suppressor effects of zinc. The enigma is that this approach and expectation has not reached fruition. The question is "why?". This article provides a discussion of relevant zinc issues that need to be considered and resolved. Important areas of research are identified as being essential for the successful application of zinc cytotoxicity/tumor suppression actions for the treatment of specific cancers.