The magic of mistletoe

The name was originally applied to Viscum album (European Mistletoe, Santalaceae), the only species native in Great Britain and much of Europe. European mistletoe, Viscum album is readily recognized by its smooth-edged oval evergreen leaves borne in pairs along the woody stem, and waxy white berries in dense clusters of 2 to 6. In America the genus Viscum does not grow wild but the Eastern Mistletoe (in the genus Phoradendron) is similar, but has shorter, broader leaves and longer clusters of 10 or more berries.

Viscum album is a poisonous plant that causes acute gastrointestinal problems including stomach pain, and diarrhea along with low pulse. However, both European Mistletoe and the North American species, Phoradendron serotinum, are commercially harvested for Christmas decorations.

But there is more to mistletoe than just an excuse to steal a kiss from beautiful woman at Christmas time!

This is the season to be jolly, eat a lot of mince pies and probably drink rather more wine than normal. It is also the season to linger under the mistletoe and hope someone fanciable comes your way!

However, it now seems that mistletoe may have more to offer than a potential romantic encounter as recent research into its anticancer properties demonstrates.

For the past 80 years European mistletoe (Viscum album) has been documented for its use in the fight against cancer it and even has its own annual international Symposium (the fifth of which has just been held in Germany) to review the latest findings in mistletoe/cancer research.

Despite conflicting results into its efficacy in the fight against cancer, many positive reports are now emerging that are making its potential hard to ignore.

Several anticancer compounds have been found in its extracts and in the past 10 years, several controlled clinical trials have been published supporting its use alongside conventional cancer treatments.

A 2010 review identified 26 randomised controlled trials focused on mistletoe use on cancer patients. Although the results for treatment of the cancer and patient survival were mixed, consistent benefits were found for quality of life, especially fatigue and sleep quality.

Its impact on chemotherapy side-effects was inconsistent. However, a more recent meta-study (covering 49 trials) confirmed a survival benefit as well as a near universal improvement in quality-of-life.

Another large German study found that cancer patients benefited from mistletoe extract and extended their survival by roughly 40% compared to non-extract users. Even more impressive results have been found in a few isolated cases. For example two years ago, a UK female diagnosed with non-Hodgkin’s lymphoma took mistletoe as a first-line therapy before chemo; the reports suggest that the therapy worked and the cancer went into remission.

In 2011, a patient with metastatic pancreatic adenocarcinoma (spreading into the regional lymph nodes and liver) started taking mistletoe extract along with palliative chemotherapy after her surgery. She showed sustained partial remission after 37 weeks of treatment, at which time other chemotherapy was stopped but the mistletoe continued. Surprisingly, 10 months later, she still showed no evidence of tumour progression.

This case was reported in the peer-reviewed German cancer journal Onkologie as results such as this even with conventional treatment are exceedingly rare for this type of cancer.

Despite these very encouraging results, conventional medicine has been slow to adopt mistletoe due to mixed results of some larger trials. However, it now seems there may be an explanation for this inconsistency. The problem seems to be the use of different mistletoe extracts in different trials, and apparently not all extracts are created equal.

Mistletoe extracts should work by stimulating the immune system and by exerting cytotoxic effects on a wide range of cancer cells. However, the mistletoe plant is itself quite poisonous (more than 2 berries or three leaves can produce toxic effects), so an extraction process is required to separate out the medicinal phytochemicals from the toxic ones.

We believe that mistletoe’s key active phytochemicals are lectins and viscotoxins (among others), but unfortunately these are not present in sufficient quantities in all available mistletoe products.

The best products are made from the whole plant extract from the leaves, shoots and fruits of the summer and winter harvest.

As a result of this accumulating evidence, two of the largest—ever cohort studies on mistletoe have been initiated in Europe (where its use is common). Both are now recruiting in multiple centres across Germany and Austria. One study will test mistletoe extract on pancreatic cancer in 400 patients; the other will test it on colorectal cancer in 800 patients. While both trials will use mistletoe in addition to conventional cancer therapies, they may be seen as a first step in proving mistletoe as a first-line therapy.

Until then, the evidence to date on mistletoe makes a convincing case for its consideration as part of any cancer therapy. Here’s hoping the results are good!

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