This article appeared in the January, 2010 issue of the Natural Medicine Journal

[return to our Home Page]

Does mistletoe help cancer patients?

January 14, 2010

Commentator:  Jacob Schor ND FABNO

Reference:  Ostermann T, Raak C, Bussing A.  Survival of cancer patients treated with mistletoe extract (Iscador): a systematic literature review. BMC Cancer. 2009 Dec 18;9(1):451.

Study Design:  Meta-analysis of 49 studies on the clinical effects of a mistletoe extract sold as Iscador on survival of cancer patients.  Outcome data were extracted and expressed as hazard ratios (HR) using standard formulas.

Results: Fifty-two publications on the clinical effects of Iscador use and survival were found. Eight of these papers were citing the same data and were excluded.  Another four studies were excluded because they were utilizing two different mistletoe extracts, Helixor and Iscador.  Oldest study was published in 1963 and the most recent 2008.  Overall 3,388 patents were treated with Iscador and 7,253 served as controls.  The majority of the studies reported positive effects. 

‘Pooled analysis of clinical studies suggests that adjuvant treatment of cancer patients with the mistletoe extract Iscador is associated with a better survival. Despite obvious limitations, and strong hints for a publication bias which limits the evidence found in this meta-analysis, one can not ignore the fact that studies with positive effects of VA-E on survival of cancer patients are accumulating.’

The medical use of mistletoe can be traced back to Druid ritual.  Rudolf Steiner popularized the use of mistletoe preparations in his system of anthroposophical medicine.  That this therapy was derived from such an esoteric source may be why research results have been inconsistent. The bias that researchers bring to their study of mistletoe may be difficult to overcome.  Results may be swayed by patient belief and non-randomized studies are inherently suspect.

This paper is the most comprehensive and yields the most positive meta-analysis to date.  There have been similar attempts at pooling data over recent years in order to gain more insight into whether mistletoe offers benefit that have not yielded such encouraging results. 

In 2003 Ernsts et al. attempted to review the randomized clinical trials but concluded that statistical pooling was not possible because the primary studies varied so much and instead simply wrote a narration of results.  In their conclusion, “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.”

Kienle and Kiene in a 2007 paper analyzed 16 randomized and 9 non-randomized controlled trials that investigated mistletoe treatment of malignant diseases. And reported that, “… the best evidence for efficacy of mistletoe therapy exists for improvement of QoL [quality of life] and reduction of side effects of cytotoxic therapies (chemotherapy, radiation).” 

Horneber et al. in a 2008 Cochrane Review that analyzed randomized controlled trials on various mistletoe preparations wrote:  “The evidence … that the application of mistletoe extracts has impact on survival or leads to an improved ability to fight cancer or to withstand anticancer treatments is weak.”  

In a June 2009 review on mistletoe effect on breast and gynecological cancers, Kienle et al.  analyzed data from “19 randomized, 16 non-randomized controlled studies, and 11 single-arm cohort studies ….”  Their analysis found, “…some positive effects in breast and gynaecological cancer.”

Reading these various outcomes reminds me of the days before I had an accountant file my income taxes.  Each time I completed the tax forms I reached a different answer as to how much I owed the government.

The positive conclusions in the most recent review by Ostermann et al. will be widely quoted by those promoting use of Iscador and probably ignored by those less inclined to its use.  Instead they will point to other reviews that were unable to show benefit, and there is no shortage of these.

As Ostermann et al, authors of the current study, conclude, “Future studies evaluating the effects of Iscador should focus on a transparent design and description of endpoints in order to provide greater insight into a treatment often being depreciated as ineffective, but highly valued by cancer patients.”

In the meantime, it is encouraging to read that this often-debated therapy, which is in such high demand by patients, may actually be of benefit.

Ernst E, Schmidt K, Steuer-Vogt MK. Mistletoe for cancer? A systematic review of randomised clinical trials. Int J Cancer. 2003 Nov 1;107(2):262-7.

Kienle GS, Kiene H. Complementary cancer therapy: a systematic review of prospective clinical trials on anthroposophic mistletoe extracts.  Eur J Med Res. 2007 Mar 26;12(3):103-19.

Horneber MA, Bueschel G, Huber R, Linde K, Rostock M. Mistletoe therapy in oncology. Cochrane Database Syst Rev. 2008 Apr 16;(2):CD003297.

Kienle GS, Glockmann A, Schink M, Kiene H. Viscum album L. extracts in breast and gynaecological cancers: a systematic review of clinical and preclinical research. J Exp Clin Cancer Res. 2009 Jun 11;28:79.