Mistletoe for Cancer Treatment

Pamela A. Popper

Wellness Forum Health


Mistletoe is a semi-parasitic plant that grows on host trees such as apple, oak, elm, pine, and birch, and has been used historically for medicinal purposes. Some research shows that mistletoe extracts, such as Iscador, stimulate the immune system and can improve outcomes for cancer patients. Extracts are also used to treat hepatitis, HIV/AIDS, to lower blood pressure, and as a general immune stimulant.

Extracts are often named based on the type of tree the plant grows on. For example, IscadoreM is from apple trees, Iscadore P is from pine trees, IscadorU comes from elm trees, and Iscador Qu is from oak trees.

Mistletoe is one of the most widely studied and used alternative treatments for cancer patients and is commonly used in Europe. A survey of German doctors showed that 80.2% used unconventional therapies for the treatment of cancer, and 44.4% of them used mistletoe extract.[i]

Mistletoe is not used as a stand-alone treatment, but rather as an adjuvant. Reported benefits include reduction in pain, better digestion, improvement in sleep and appetite, decrease in fatigue, and decreased side effects from traditional treatment. Some studies have reported reduction in tumor growth, and there is limited evidence concerning tumor regression.

Research results for mistletoe extract are mixed, but many studies have shown improvements in quality of life and reduction of side effects for those undergoing cancer treatment. In one study of 1442 breast cancer patients who were followed for about five years, 54.1% of the control patients developed adverse drug events from conventional therapy, while only 16.3% of the patients taking mistletoe had such side effects. The patients taking mistletoe also lived significantly longer. The researchers concluded that mistletoe was both safe and effective for cancer patients.[ii]

A randomized, double-blind clinical trial concluded that standardized mistletoe injections significantly improved quality of life for breast cancer patients undergoing chemotherapy. Symptoms like nausea, numbness, and tingling were reduced, and patients taking mistletoe experienced less hair loss than those taking a placebo.[iii]

Another trial including breast cancer, ovarian cancer, and small-cell lung cancer patients showed that subjects taking mistletoe extract experienced a 42% reduced incidence of side effects associated with chemotherapy than patients taking placebo.[iv]

When used as an adjuvant, mistletoe extract has been shown to increase the cytotoxicity of chemotherapy drugs,[v] and in a literature review it was shown to reduce mortality rates.[vi]

Not all studies have not shown favorable results, however. One study showed that the product was useless for patients with high-risk melanoma.[vii] And a report of a 73-year-old man with Non-Hodgkin lymphoma who developed subcutaneous nodes of the abdominal wall at the site of mistletoe injections is concerning. Discontinuation of the mistletoe prevented the development of additional nodes. The researchers concluded, “There are pointers that high concentrations of mistletoe preparations subcutaneously injected can have a growth-promoting action on cells of a centrocytic lymphoma. As part of a leukaemic “wash-out”, these cells reach the subcutaneous tissue. This proliferative stimulus may have been mediated by a high local concentration of interleukin-6 liberated from the skin by mistletoe lectins.”[viii]

Mistletoe extract is widely available by prescription in Europe and is most often administered subcutaneously. It can also be taken orally, but most research studies have used the subcutaneous version. It is not currently approved by the U.S. Food and Drug Administration,[ix] and its use as an injectable in the U.S. is only permitted in clinical trials.[x] Physicians in the U.S. can obtain it through the FDA’s “compassionate use program,” which allows patients for whom there are no other legal options for treatment to access unapproved drugs. The product can be ordered from Weleda AG (www.usa.weleda.com).

Mistletoe extract is contraindicated for pregnant women (it can stimulate uterine contractions) and for anyone taking a P450 3A4 substrate drug.

Common side effects include fever, chills, elevated white blood cell count, headache, chest pain, orthostatic hypotension, and reaction at the injection site. Less common but more serious side effects include diarrhea, vomiting, low blood pressure, low heart rate, losing consciousness, increase plasma glucose levels, itching and rash.

It is important to note that the berries and leaves of mistletoe are poisonous – just 2 berries and 3 leaves can cause deadly side effects. Mistletoe products should only be used while under the care of a physician who is knowledgeable about them and who sources them from reputable manufacturers. While not all research studies show that mistletoe is effective, it is safe for most cancer patients, and has a long track record of mostly successful use in Europe. It is difficult to fathom the rationale for making it difficult for cancer patients to obtain the product, particularly since traditional oncology has little to offer for many cancer patients. For many people, it worth the effort to find an open-minded doctor to prescribe it.

[i] Munstedt K, Entezami A, Kullmer U. “Oncologic mistletoe therapy: physicians’ use and estimation of efficiency.” Dtsch Med Wochenschr. 2000 Oct;125(41):1222-6

[ii] Bock PR, Friedel WE, Hanisch J, Karasmann M, Schneider B. “Efficacy and safety of long-term complementary treatment with standardized European mistletoe extract (Viscum album L) in addition to the conventional adjuvant oncologic therapy in patients with primary non-metastasized mammary carcinoma. Results of a multi-center, comparative, epidemiological cohort study in Germany and Switzerland.” Arzneimittelforschung. 2004;54:456-466

[iii] Semiglazov VF, Stepula VV, Dudov A Schnitker J, Mengs U. “Quality of life is improved in breast cancer patients by Standardised Mistletoe Extract PS76A2 during chemotherapy and follow-up: a randomised, placebo-controlled, double-blind, multicentre clinical trial.” Anticancer Res. 2006 Mar-Apr;26(2B):1519-1529

[iv] Piao BK, Wang YX, Xie GR, et al. “Impact of complementary mistletoe extract treatment on quality of life in breast, ovarian and non-small cell lung cancer patients. A prospective randomized controlled clinical trial.” Anticancer Res. 2004 Jan-Feb;24(1):303-309

[v] Bantel H, Engels IH, Voelter W, Schulze-Ostoff K, Wesselberg S. “Mistletoe Lectin Activates Capase-8/FLICE Independently of Death Receptor Signaling and Enhances Anticancer Drug-Induced Apoptosis.” Cancer Res 1999 May;59:2083-2090

[vi] OStermann T< Raak C, Bussing A. “Survival of cancer patients treated with mistletoe extract (Iscador): a systematic literature review.” BMC Cancer 2009 Dec;9:451

[vii] Kleeberg UR, Suciu S, Brocker EB, et al. “Final results of the EORTC 18871/DKG 80-1 randomised phase III trial. rIFN-alpha2b versus rIFN-gamma versus ISCADOR M versus observation after surgery in melanoma patients with either high-risk primary (thickness >3 mm) or regional lymph node metastasis.” Eur J Cancer. 2004 Feb;40(3):390-402

[viii] Hagenah W, Dorges I, Gafumbegete E, Wagner T. “[Subcutaneous manifestations of a centrocytic non-Hodgkin lymphoma at the injection site of a mistletoe preparation]” Dtsch Med Wochenschr. 1998 Aug;123(34-35):1001-4

[ix] https://www.cancer.gov/about-cancer/treatment/cam/patient/mistletoe-pdq

[x] https://nccih.nih.gov/health/mistletoe