Lysozyme and cancer: role of exogenous lysozyme as anticancer agent (review).

The use of lysozyme preparations in the treatment of tumor diseases is based on more than 30 years' experience, using different methodologies and showing various results from which suggestions on the mechanism of action were derived. Lysozymes have no established place in the treatment of human tumors in spite of some interesting findings described in some reports. Nevertheless, many studies have confirmed the tumor-inhibitory activity of lysozyme treatment in a number of experimental tumors. The first half of the sixties saw increased attention on the part of scientists to the antitumor activity of lysozyme in many in vivo experimental systems of animal tumors. All of them emphasized tumor inhibitory effects after administration of lysozyme by various routes including admixture with tumor cells, peritumor and intratumor treatments, or indirectly by systemic injections and oral treatment. From these observations, at least two possible mechanisms of action can be derived, both involving the activation of the immune reactivity of the host. Lysozyme can directly activate immune cells or it can increase tumor cell immunogenicity. Alternatively, lysozyme can liberate substances from bacteria (peptidoglycans and/or polyribopyrimidinic acids) responsible for immunopotentiation and therefore antitumor activity. The present work will focus on the possibilities offered by the use of lysozyme(s) in cancer management, citing the evidence to be found in the literature with the aim of contributing to a better understanding of the activity and the role of lysozyme in the treatment of neoplastic diseases.