What is mistletoe?
Mistletoe is a semiparasitic plant that grows on many types of trees, including apple, oak, maple, elm, pine, and poplar. It has been used for hundreds of years to treat medical conditions such as epilepsy, asthma, hypertension, headaches, menopausal symptoms, infertility, dermatitis, arthritis, and rheumatism.
Mistletoe extracts are one of the most widely studied complementary and alternative medicine therapies for cancer. In Europe, mistletoe extracts are among the most prescribed therapies for cancer patients.
Mistletoe products vary, based on the following factors:
- The species of mistletoe.
- The type of host tree on which the mistletoe grows.
- The time of year the plant is picked.
- The type of extract used and if it is made with homeopathic methods.
- The company that makes the product.
Mistletoe extracts are made in water-based solutions or solutions of water and alcohol. Mistletoe products may be named by the type of tree on which the plant grows. For example, IscadorM is from apple trees, IscadorP comes from pine trees, IscadorQu is from oak trees, and IscadorU comes from elm trees.
How are mistletoe extracts given?
Mistletoe extracts are usually given by an injection under the skin. Less common ways to give mistletoe extracts include by mouth, into a vein, into the pleural cavity, or into a tumor.
What laboratory or animal studies have been done using mistletoe extracts?
In laboratory studies, tumor cells are used to test a substance to find out if it is likely to have any anticancer effects. In animal studies, tests are done to see if a drug, procedure, or treatment is safe and effective in animals. Laboratory and animal studies are done before a substance is tested in people.
Laboratory and animal studies have been done to test the effects of mistletoe extracts. For information on laboratory and animal studies done using mistletoe extracts, see the Laboratory/Animal/Preclinical Studies in the health professional version of this summary.
Have any studies of mistletoe extracts been done in people with cancer?
Most clinical trials using mistletoe extracts to treat cancer have been done in Europe. Many studies use mistletoe products as adjuvant therapy in patients with cancer. Although these trials have reported mistletoe extracts to work, the following problems have been reported:
- Small trial size.
- Lack of patient information.
- Lack of dose information.
- Study design.
Studies with large numbers of patients reported the following:
- A study in postoperative early-stage breast cancer patients compared standard treatment and mistletoe extract to standard treatment alone. Less adverse drug reactions were reported in the group given mistletoe extract.
- Another study in breast cancer patients compared survival between those who had standard therapy and mistletoe extract and those who had standard therapy alone. Improved survival was reported in the group given mistletoe extract.
- A retrospective cohort study done between 1993 and 2000 looked at the use of mistletoe extract as long-term adjuvant therapy in patients treated with chemotherapy and/or radiation therapy for colorectal cancer that had not spread. The study found that patients treated with mistletoe extract had longer disease-free survival, fewer adverse events, and better symptom relief than patients who did not receive mistletoe extract as adjuvant therapy.
- A study published in 2013 looked at the use of mistletoe extract in advanced or metastatic pancreatic cancer. Patients received best supportive care and were randomly assigned to receive either mistletoe extract or no anticancer therapy. Results from the study showed that patients treated with mistletoe extract had improved survival compared with those who did not receive mistletoe extract.
Non-small cell lung cancer
- Two randomized clinical trials that compared chemotherapy to mistletoe extract in non-small cell lung cancer patients reported no differences between the two groups in improved quality of life.
- A study done between 1978 and 1987 looked at the use of mistletoe extract in non-small cell lung cancer that could not be treated with surgery. Patients were randomly assigned to receive one of 3 treatments: (1) a mistletoe extract injection; (2) an injection made from a sheep spleen said to stimulate the immune system and have antitumor effects; (3) a placebo injection of vitamin B. Results among the 3 groups were no different in survival or tumor response. It was noted that more patients in the mistletoe extract group than in the other groups reported an improved sense of well-being.
- A randomized clinical trial in melanoma patients treated with mistletoe extract for 1 year found that there was no increase in survival time.
Reviews of combined clinical trials
Reviews have looked at the effects of mistletoe extract on quality of life, survival, and symptom relief in different types of cancer. Some of the studies were well designed and reported benefits for patients, while others were not. A few studies reported a difference in survival or quality of life in patients who received mistletoe extract compared with those who did not.
For more information on mistletoe extract studies, see the health professional version of Mistletoe Extracts.
Have any side effects or risks been reported from mistletoe extracts?
Side effects from the use of mistletoe extracts include soreness and inflammation at injection sites, headache, fever, and chills. A few cases of severe allergic reactions, including anaphylactic shock, have been reported.
One review reported that treatment with mistletoe extract did not reduce immune system response. High doses of mistletoe extract damaged the liver in some cases, but the damage was repaired. Another review reported adverse effects that included circulatory problems, thrombophlebitis, swelling of lymph nodes, and allergic reactions.
In an observational cohort study, three types of mistletoe extract (Iscador, Helixor, and abnobaVISCUM) that were given were found to be safe in a small group of cancer patients with autoimmune diseases.
Is mistletoe extract approved by the U. S. Food and Drug Administration (FDA) for use as a cancer treatment in the United States?
The FDA has not approved the use of mistletoe extract as a treatment for cancer or any other medical condition.