Mistletoe treatment for cancer review of controlled trials in humans

This review assesses the evidence of the efficacy of mistletoe extracts in cancer patients from controlled clinical trials in humans. We used a list of predefined criteria for good methodology to select the trials which had the highest quality and interpreted the results with emphasis on the quality. An extensive search of the literature yielded 11 controlled trials in which at least an attempt was made for unbiased allocation into the contrasted treatment groups. The average quality of the trials appeared to be disappointingly poor. It concerned trials for bronchus carcinoma, colorectal carcinoma, mamma carcinoma, gastric cancer and female genital cancer. In the trials the results were in favour of mistletoe treatment; the principle endpoint was mostly survival time. Only one trial could not show a beneficial effect, but this was the trial with the highest methodological score. Well performed randomized, double-blind clinical trials on carefully chosen patient populations are needed in order to make assessments of any efficacy. Further evidence should also consist of a more solid demonstration of the mechanisms of action from laboratory studies. Standardization methods on active substances should be improved as there are apparent component variations between, but also within the preparations which were used in clinical trials. Considering the state of affairs we cannot recommend the use of mistletoe extracts in the treatment of cancer patients with an exception for patients involved in clinical trials.