Mistletoe Extracts Standardised in terms of Mistletoe Lectins (ML I) in Oncology: Current State of Clinical Research

Abstract

Purpose: The aim of this review is to present the current state of clinical oncological research on mistletoe extracts standardised in terms of the active substance mistletoe lectin. Methods: This review focuses on studies with clearly defined mistletoe extracts standardised in terms of mistletoe lectins I, II, and III (calculated as mistletoe lectin I, ML I) which belong to the category of rational phytotherapy. That means that studies with anthroposophic or homeopathic drugs will not be included. Results: There are several preclinical studies that show a cytotoxic and immunostimulating effect of mistletoe extracts, predominantly on the cellular immune system. The clinical database, however, is not as good as the experimental results. So far, no direct anticancer action or any improvement in time to tumour progression or overall survival in cancer patients has been seen. The first results of a randomised phase III study suggest that additive administration of a mistletoe preparation may improve the quality of life. Conclusion: Mistletoe therapy has not gained an established place in oncology. Further, well-planned randomised clinical investigations will be necessary to verify the first positive findings with regard to an improvement of quality of life in cancer patients.