Mistletoe Is Unproven as a Remedy to Cancer

When my husband was a boy, he would go with his father in early December to a cousin’s farm in southern Maryland to cut down a Christmas tree and shoot mistletoe out of the tops of oak trees with a shotgun. The mistletoe, of course, was then hung above doorways as a holiday decoration and invitation to a kiss.

That tradition continues today, and it is a very old tradition indeed. In ancient days, mistletoe was believed to have the power to increase fertility, hence the kiss, but that was only one of its many applications. In folklore, mistletoe is described as a cure-all; a treatment for anything and everything. It has been used since the time of the ancient Greeks and Druids to treat infertility, headaches, hypertension, menopausal symptoms, arthritis and rheumatism, and more. In the 16th century, mistletoe became a treatment for epilepsy and other nervous system disorders.

Today, mistletoe is used as a tranquilizer and to relieve rheumatoid arthritis. It is also used as an alternative therapy to treat whooping cough, diarrhea, gout, hysteria and other mental conditions, internal bleeding, high blood pressure, dizziness, menstrual problems, asthma and so on. Recently, a type of mistletoe called Iscador was in the news when actress Suzanne Somers went on the talk-show circuit to speak about how she decided to use the therapy to treat her breast cancer.

In effect, this medicinal herb remains the false panacea it was millenniums ago, in large part because its ability to treat these and other ailments has not been scientifically validated or invalidated.

Mistletoe was first proposed as a cancer remedy in 1920 by Austrian Rudolph Steiner, the founder of a spiritual philosophy movement called anthroposophy. Despite the absence of scientific documentation of its value, it is still offered as a component of cancer treatment in several European clinics, where it is claimed to relieve the symptoms of cancer and cancer treatment. Mistletoe is typically used along with chemotherapy and other mainstream treatments; rarely instead of chemotherapy or other needed interventions. Some people believe mistletoe helps cure cancer, but no evidence supports such a claim.

Scientific studies show that mistletoe, like many herbs and other botanicals, may stimulate the immune system and increase the number and activity of white blood cells. There is no evidence, however, that this enhanced immunity destroys or helps destroy cancer cells. Many studies of patients with breast cancer and other types of malignancies have been conducted, mainly in Europe. A major problem with these studies is that many if not most were not designed to meet rigorous international scientific standards, so the results are not definitive.

In addition, there are many brands of mistletoe, including Abnobaviscom, Eurixor, Helixor, Iscador, Isorel and Vysorel. (None is available legally in the United States because no one has applied to the Food and Drug Administration to study mistletoe as a treatment for cancer or other illnesses. Therefore, mistletoe products have not been tested for safety and value by the FDA.)

Different studies have used different brands of mistletoe. Just to complicate the research situation even further, there are many different kinds of mistletoe. Mistletoe is a parasitic plant that attaches itself to the tops of various trees, such as elm, pine, oak, birch, maple and apple. The chemical content and composition of mistletoe products vary substantially according to the host tree, the species of mistletoe and other factors.

All of this variation, which is reflected in the research studies, renders their results even less meaningful. Bottom line: Mistletoe products remain unproved. They have no documented value against cancer, and I have never heard of an oncologist in the United States prescribing such treatment.

Mistletoe plants and berries actually are toxic to humans. Eating the berries can cause blurred vision, nausea and vomiting, irregular heartbeat, abdominal pain and diarrhea. Public reaction to media reports about Iscador and other mistletoe varieties reflects how people often hear only part of the story about “miracle cures.” Such is the case with recent publicity about mistletoe as a treatment for breast cancer.

After a breast tumor is removed surgically, the area around the tumor is treated with radiation therapy to kill any remaining cancer cells. But some cells may have drifted away through the bloodstream and set up shop elsewhere in the body. These are the targets of chemotherapy. If these cancer cells are not destroyed, they can establish themselves as metastatic tumor sites, becoming new cancerous growths that endanger the life that houses them. Herbs can be extremely helpful, and many effective cancer treatments, such as Taxol and vincristine, are derived from botanicals. Herbs are, after all, dilute pharmaceuticals.

Cancer is a powerful foe, and it requires an equally powerful attack. Chemotherapy, not mistletoe or other dilute pharmaceuticals, kills cancer cells.

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Barrie Cassileth, PhD, is chief of integrative medicine at Memorial Sloan-Kettering Cancer Center in New York. She can be reached at BarrieC@Juno.com. Her column appears the first Monday of the month.