Can Mistletoe Help Treat Cancer?

Check out this answer from Consensus:

The current scientific evidence does not provide strong support for the use of mistletoe extracts in cancer treatment. While some studies suggest potential benefits in terms of QoL, the evidence is inconsistent and often of low methodological quality. The impact of mistletoe extracts on survival remains unclear, with most high-quality studies showing no significant benefit. More rigorous, well-designed clinical trials are needed to conclusively determine the efficacy and safety of mistletoe extracts in cancer therapy. Until then, the use of mistletoe extracts should be approached with caution, and patients should be encouraged to participate in clinical trials to further investigate its potential benefits and risks.

Mistletoe extracts have been used in various traditional and complementary medicine practices, particularly in Europe, for the treatment of cancer. Despite its widespread use, the efficacy and safety of mistletoe extracts in cancer therapy remain highly controversial. This article aims to review the current scientific evidence regarding the use of mistletoe in cancer treatment, focusing on its impact on survival, quality of life (QoL), and safety.

Efficacy of Mistletoe in Cancer Treatment

Survival Outcomes

Several studies have investigated the impact of mistletoe extracts on the survival of cancer patients. A systematic review and meta-analysis of non-fermented mistletoe extracts suggested a potential positive impact on overall survival, with a pooled hazard ratio indicating a survival benefit8. However, the studies included in this review displayed a moderate to high risk of bias, and the effect estimates became non-significant when active comparators were included in the analysis8. Another review found that while some trials showed evidence of a survival benefit, none of these trials were of high methodological quality3. Overall, the evidence supporting the use of mistletoe extracts to improve survival in cancer patients is weak and inconsistent2 3.

Quality of Life

The impact of mistletoe extracts on the quality of life of cancer patients has been more extensively studied. A systematic review and meta-analysis reported a significant, medium-sized effect on global QoL in cancer patients treated with mistletoe extracts compared to controls5 7. The effect was stronger in younger patients, with longer treatment durations, and in studies with lower risk of bias5. However, other reviews have found that studies with better methodological quality show less or no effect on QoL4. Despite some positive findings, the overall evidence remains inconclusive due to the high risk of bias in many studies1 4.

Safety and Tolerability

Mistletoe extracts are generally well-tolerated, with few reported side effects. A review of randomized controlled trials (RCTs) found that mistletoe extracts were usually well tolerated, with side effects depending on the dose3. Another study reported no significant changes in cellular immune reactions or QoL in patients treated with mistletoe extracts9. However, the safety profile of mistletoe extracts needs further investigation through high-quality, independent clinical research3.

Can Mistletoe help treat cancer?

Gunver Kienle has answered Likely

An expert from University Medical Center Freiburg in Clinical Research, Alternative Medicine, Oncology, Geriatrics, Clinical Trials

Mistletoe extracts are applied in addition to standard cancer treatments, particularly to improve quality of life. 

Mistletoe compounds are immunologically active, highly cytotoxic and induce apoptosis in cancer cells. 

Most of the clinical trials have methodologic weaknesses. The methodological stronger ones describe an improved quality of life, particularly improved emotional well-being, appetite and reduced fatigue, depression and anxiety. A large randomized controlled trial on advanced or metastatic pancreatic cancer receiving best supportive care showed a highly significant increase of survival in patients treated with mistletoe, compared to the control patients. Large randomized controlled trials currently further investigate these observations.

 Beztsinna, N., de Matos, M.B.C., Walther, J. et al. Quantitative analysis of receptor-mediated uptake and pro-apoptotic activity of mistletoe lectin-1 by high content imaging. Sci Rep 8, 2768 (2018). https://doi.org/10.1038/s41598-018-20915-y

Szurpnicka, A., Kowalczuk, A., & Szterk, A. (2020). Biological activity of mistletoe: in vitro and in vivo studies and mechanisms of action. Archives of pharmacal research, 43(6), 593–629. https://doi.org/10.1007/s12272-020-01247-w

Kienle, G. S., & Kiene, H. (2010). Review article: Influence of Viscum album L (European mistletoe) extracts on quality of life in cancer patients: a systematic review of controlled clinical studies. Integrative cancer therapies, 9(2), 142–157. https://doi.org/10.1177/1534735410369673

Loef, M., & Walach, H. (2020). Quality of life in cancer patients treated with mistletoe: a systematic review and meta-analysis. BMC complementary medicine and therapies, 20(1), 227. https://doi.org/10.1186/s12906-020-03013-3

Tröger, W., Galun, D., Reif, M., Schumann, A., Stanković, N., & Milićević, M. (2013). Viscum album [L.] extract therapy in patients with locally advanced or metastatic pancreatic cancer: a randomised clinical trial on overall survival. European journal of cancer, 49(18), 3788–3797. https://doi.org/10.1016/j.ejca.2013.06.043

Tröger, W., Galun, D., Reif, M., Schumann, A., Stanković, N., & Milićević, M. (2014). Quality of life of patients with advanced pancreatic cancer during treatment with mistletoe: a randomized controlled trial. Deutsches Arzteblatt international, 111(29-30), 493–502. https://doi.org/10.3238/arztebl.2014.0493

Can Mistletoe help treat cancer?

Harald Walach has answered Near Certain

An expert from Poznan University of Medical Sciences  in Mindfulness, Alternative Medicine

We did a meta-analysis of all mistletoe studies: quality of life improves by a clinically and statistically significant margin (Loef, M., & Walach, H. (2020). Quality of life in cancer patients treated with mistletoe: a systematic review and meta-analysis. BMC Complementary Medicine and Therapies, 20(2027). doi:10.1186/s12906-020-03013-3). My colleagues did one on survival (Ostermann, T., Appelbaum, S., Poier, D., Boehm, K., Raak, C., & Büssing, A. (2020). A Systematic Review and Meta-Analysis on the Survival of Cancer Patients Treated with a Fermented Viscum album L. Extract (Iscador): An Update of Findings. Complementary Medicine Research, 27(4), 260-271. doi:10.1159/000505202). The Hazard Ratio = 0.59; i.e. mistletoe treated patients had about a 41% higher chance of living longer. This is not significant for lung cancer, which seems to be difficult anyway.

I.e.: mistletoe treatment improves quality of life, and possibly also survival. But these studies were all with fermented products, and there are also unfermented ones, which we are currently analysing, but we are not finished yet.