Mistletoe as Cancer Treatment Unlikely

A review of multiple studies examining the use of mistletoe extract (Viscum album) to treat a variety of cancers has failed to demonstrate any benefit in shrinking tumors or increasing life span, according to a new report in the International Journal of Cancer (2003;107:262–7).

Mistletoe is more popularly known for its seasonal appearance around Christmas time, but a few human studies suggest it can be used therapeutically to boost immune function. However, the proposed benefits of mistletoe in the treatment of cancer have been based only on the results from test tube studies and have not been confirmed in human studies. Currently, there are three different mistletoe extracts available for use, but all three are designed to be injected intravenously and cannot be administered to oneself at home. These extracts have been used widely in Europe, but are not available in the United States.

In the new study, the results from ten previously published controlled trials were pooled, using a technique called meta-analysis. Meta-analyses are based on the premise that combining the results of many studies allows one to draw more definitive conclusions. Each of the ten studies in this analysis had assessed the effectiveness of various mistletoe extracts in the treatment of different forms of cancer. Most of the studies reviewed had considerable weaknesses in terms of design, reporting of results, or both.

The studies evaluated in the meta-analysis examined the use of mistletoe extract in the treatment of colon, lung (non-small-cell), brain (glioma), breast, head, neck, skin, and bladder cancers, either alone or in conjunction with conventional cancer care. Many of these studies looked at people with advanced stages of cancer. Some of the individual studies suggested a slight improvement in quality of life, but when the results of the studies were pooled together, no significant benefit of mistletoe was found. The studies that reported a better quality of life were deemed to be of poor quality by the reviewers. No significant benefit was observed in any of the high-quality studies and mistletoe extract did not increase the effectiveness of chemotherapy.

Despite the lack of solid data to support its use in cancer care, many practitioners who treat people with cancer continue to recommend this treatment. More than $30 million (U.S.) is spent each year on mistletoe extracts in Germany and sales have increased by 20% each year in the last several years. Mistletoe extracts cause adverse side effects in up to 45% of those who use the products, including fever, local reaction at site of injection, swollen lymph nodes, headache, severe allergic reactions, circulatory problems, and liver damage. Given the potential toxicity of mistletoe extract, people with cancer who prefer to use natural substances as part of their cancer care should avoid using it and seek other safer treatments for their particular type of cancer.

Darin Ingels, ND, MT (ASCP), received his bachelor’s degree from Purdue University and his Doctorate of Naturopathic Medicine from Bastyr University in Kenmore, WA. Dr. Ingels is the author of The Natural Pharmacist: Lowering Cholesterol (Prima, 1999) and Natural Treatments for High Cholesterol (Prima, 2000). He currently is in private practice at New England Family Health Associates located in Southport, CT, where he specializes in environmental medicine and allergies. Dr. Ingels is a regular contributor to Healthnotes and Healthnotes Newswire.

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