Mistletoe treatment of cancer patients was the idea of Rudolf Steiner. Mistletoe grows on a host tree like a parasite and eventually might kill it. This seems similar to a cancer killing a patient, and Steiner – influenced by the homeopathic ‘like cures like’ notion – thought that mistletoe should thus be an ideal treatment of all cancers. Despite the naivety of this concept, it somehow did catch on, and mistletoe has now become the number one cancer SCAM in Europe which is spreading fast also to the US and other countries.
But, as we all know, the fact that a therapy lacks plausibility does not necessarily mean that it is clinically useless. To decide, we need clinical trials; and to be sure, we need rigorous reviews of all reliable trials. Two such papers have just been published.
The aim of the systematic review was to give an extensive overview about current state of research concerning mistletoe therapy of oncologic patients regarding survival, quality of life and safety.
The authors extensive literature searches identified 3647 hits and 28 publications with 2639 patients were finally included in this review. Mistletoe was used in bladder cancer, breast cancer, other gynecological cancers (cervical cancer, corpus uteri cancer, and ovarian cancer), colorectal cancer, other gastrointestinal cancer (gastric cancer and pancreatic cancer), glioma, head and neck cancer, lung cancer, melanoma and osteosarcoma. In nearly all studies, mistletoe was added to a conventional therapy. Patient relevant endpoints were overall survival (14 studies, n = 1054), progression- or disease-free survival or tumor response (10 studies, n = 1091). Most studies did not show any effect of mistletoe on survival. Especially high quality studies did not show any benefit.
The authors concluded that, with respect to survival, a thorough review of the literature does not provide any indication to prescribe mistletoe to patients.
The aim of the second systematic review by the same team was to give an extensive overview about the current state of evidence concerning mistletoe therapy of oncologic patients regarding quality of life and side effects of cancer treatments. The same studies were used for this analysis as in the first review. Regarding quality of life, 17 publications reported results. Studies with better methodological quality showed less or no effects on quality of life.
The authors concluded that with respect to quality of life or reduction of treatment-associated side effects, a thorough review of the literature does not provide any indication to prescribe mistletoe to patients with cancer.
In 2003, we published a systematic review of the same subject. Here is its abstract:
Mistletoe extracts are widely used in the treatment of cancer. The results of clinical trials are however highly inconsistent. We therefore conducted a systematic review of all randomised clinical trials of this unconventional therapy. Eight databases were searched to identify all studies that met our inclusion/exclusion criteria. Data were independently validated and extracted by 2 authors and checked by the 3rd according to predefined criteria. Statistical pooling was not possible because of the heterogeneity of the primary studies. Therefore a narrative systematic review was conducted. Ten trials could be included. Most of the studies had considerable weaknesses in terms of study design, reporting or both. Some of the weaker studies implied benefits of mistletoe extracts, particularly in terms of quality of life. None of the methodologically stronger trials exhibited efficacy in terms of quality of life, survival or other outcome measures. Rigorous trials of mistletoe extracts fail to demonstrate efficacy of this therapy.
As we see, 16 years and 18 additional trials have changed nothing!
I therefore think that it is time to call it a day. We should stop the funding for further research into this dead-end alley. More importantly, we must stop giving false hope to cancer patients. All that mistletoe therapy truly does is to support a multi-million Euro industry.