[The mistletoe myth--claims, reality and provable perspectives].

Intuition guided R. Steiner to refer to mistletoe as the future remedy for cancer. He proposed that its spiritual qualities support re-establishment of the harmonious integration of the alleged four different entities of human existence in a patient. The assumption of potency without chemical basis is derived from the dogmatic system of anthroposophic reasoning. It explains the evidently similar claim of clinical efficiency for the proprietary mistletoe extracts despite the lack of information on the actual contents of the complex mixtures and despite the conspicuous diversity of methods of manufacture for these products. Thorough scientific analysis of the published clinical experience does not justify this claim. Due to the increasing reference to defined substances in advertisements for commercial extracts, they should no longer avoid rigorous testing according to common quality standards. Interdisciplinary research efforts on the immunomodulatory galactoside-binding lectin illustrate how to yield a clinically testable substance from an ill-defined extract, thereby providing a notable example for rational investigation of unconventional treatment modalities.