MD, PhD, FMedSci, FRSB, FRCP, FRCPEd

Cancer patients are understandably desperate and leave no stone unturned to improve their prognosis. Thus they become easy prey of charlatans who claim that this or that alternative therapy will cure them or improve their outlook. One of the most popular alternative cancer therapies is mistletoe, a treatment dreamt up by Rudolf Steiner on the basis of the ‘like cures like’ principle: the mistletoe plant grows on a host tree like a cancer in the human body. One of many websites on this subject, for instance, states:

Mistletoe therapy

  • integrates with conventional cancer treatments
  • can be used for a wide range of cancers
  • may be started at any stage of the illness….

potential benefits…include:

  • Improved quality of life
  • generally feeling better
  • increased appetite and weight
  • less tired/more energy
  • reduced pain
  • better sleep pattern
  • felling more hopeful and motivated
  • reduced adverse effects from chemo and radiotherapy
  • reduced risk of cancer spread and recurrence
  • increased life expectancy.

Mistletoe extracts have been shown in studies to:

  • stimulate the immune system
  • cause cancer cell death
  • protect healthy cells against harmful effects of radiation and chemotherapy.

In fact, the debate about the efficacy of mistletoe either as a cancer cure, a supportive therapy, or a palliative measure is often less than rational and seems never-ending.

The latest contribution to this saga comes from US oncologists who published a phase I study of gemcitabine (GEM) and mistletoe in advanced solid cancers (ASC). The trial was aimed at evaluating: (1) safety, toxicity, and maximum tolerated dose (MTD), (2) absolute neutrophil count (ANC) recovery, (3) formation of mistletoe lectin antibodies (ML ab), (4) cytokine plasma concentrations, (5) clinical response, and (6) pharmacokinetics of GEM.

A total of 44 study participants were enrolled; 20 were treated in stage I (mistletoe dose escalation phase) and 24 in stage II (gemcitabine dose escalation phase). All patients had stage IV disease; the majority had received previous chemo-, hormonal, immunological, or radiation therapy, and 23% were chemotherapy-naïve.

Patients were treated with increasing doses of a mistletoe-extract (HELIXOR Apis (A), growing on fir trees) plus a fixed GEM dose in stage I, and with increasing doses of GEM plus a fixed dose of mistletoe in stage II. Response in stage IV ASC was assessed with descriptive statistics. Statistical analyses examined clinical response/survival and ANC recovery.

The results show that dose-limiting toxicities were neutropenia, thrombocytopenia, acute renal failure, and cellulitis, attributed to mistletoe. GEM 1380 mg/m2 and mistletoe 250 mg combined were the MTD. Of the 44 patients, 24 developed non-neutropenic fever and flu-like syndrome. GEM pharmacokinetics were unaffected by mistletoe. All patients developed ML3 IgG antibodies. ANC showed a trend to increase between baseline and cycle 2 in stage I dose escalation.

6% of patients showed a partial response, and 42% had stable disease. Of the 44 study participants, three died during the study, 10 participants requested to terminate the study, 23 participants progressed while on study, one terminated the study due to a dose limiting toxicity, 6 left due to complicating disease issues which may be tied to progression, and one voluntarily withdrew.

An attempt was made to follow study subjects once they terminated study treatment until death. At the last attempt to contact former participants, three were still alive and five others were lost to follow-up. The median time to death of any cause was approximately 200 days. Compliance with mistletoe injections was high.

The authors explain that a partial response rate of 6% is comparable to what would be expected from single agent gemcitabine in this population of patients with advanced, mostly heavily pretreated carcinomas. The median survival from study enrollment of about 200 days is within the range of what would be expected from single agent gemcitabine.

The authors concluded that GEM plus mistletoe is well tolerated. No botanical/drug interactions were observed. Clinical response  is similar to GEM alone.

These results are hardly encouraging but they originate from just one (not particularly rigorous) study and might thus not be reliable. So, what does the totality of the reliable evidence tell us? Our 2003 systematic review of 10 RCTs found that 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.

Will this stop the highly lucrative trade in mistletoe extracts? will it prevent desperate cancer patients being misled about the value of mistletoe treatment? I fear not.

6 Responses to Mistletoe for cancer: the saga continues

  • Years ago, when I first acquired high blood pressure at the age of 40 (family history of hypertension and CHD), I didn’t want to accept the idea let alone take–gasp!– pills. I fell into a vortex of woo, trying anything I heard about such as garlic, all sorts of herbs, and finally was made aware of…mistletoe! This was before the internet, of course, so I was never able to find any mistletoe preparations at my local woo shops.

    Luckily, I was jarred into reality by a very sensible nurse who upon taking my bp, sat me down and sternly told me I was not going anywhere until she called my doctor and obtained an rx for bp meds. Something snapped (thankfully) and I complied. My only regret now, of course, is that I delayed in treating my hypertension and put unnecessary strain on my body in the meantime, which turned out to be about seven years.

    I did find that losing weight lowered my bp (and improved other CHD risk factors), and I was able to reduce meds to a minimum dosage. I also avoid salt as I seem to be one of the salt-sensitive, which is probably also an inherited trait. Maintaining the weight loss is a constant challenge as is salt-avoidance, but it has resulted in a current trial of stopping bp meds due to consistent lower than normal readings in spite of the encroachment of old age!

    So, I will keep my mistletoe in the doorway, in hopes of a few kisses, thank you, and say no the cookies and pies.

  • But does that mean that the famous and well respected hospitals in Switzerland using this therapy ( Lukas Clinic/Paracelsus Clinic) are barking up the wrong tree….. Can’t believe they would still do this if they were not supported by some
    results.???

  • You asked for some direct evidence from clinical trials?

    Here you are:
    http://www.ncbi.nlm.nih.gov/pubmed/23890767 or

    http://ar.iiarjournals.org/content/24/1/303.long

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