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Disclaimer:  This information is not meant as direct medical advice. Readers should always review options with their local medical team. This is the sole opinion of Dr. Meakin based on literature review at the time of the blog and may change as new evidence evolves.

Mistletoe As Cancer Therapy

Mistletoe - from folklore to the forefront of modern medicine, is it ready for primetime?

Reviewing the Current Status of Mistletoe Extracts in Cancer

Mistletoe is a semiparasitic evergreen shrub that grows on the branches of deciduous and coniferous trees.(1) To date, botanists have identified over 1,500 species of mistletoe, many of which have been used since antiquity to treat numerous medical maladies.(2) Its diverse applications, ranging from pain control to diabetes, reflects the variety of biologically active compounds found in its leaves, stems, and berries.(1) The lectins and viscotoxins associated with mistletoe primarily account for the plant’s immunomodulatory effects;(3,4) results from several studies suggest that its phenolic acids, triterpene acids, and non-polar compounds confer additional anticancer properties.(5,6,7) Because complete mistletoe extract appears to inhibit tumor cells more effectively than isolated compounds, it is very likely that there are synergistic modes of action among the plant’s different compounds.(8)

Mistletoe lectins are glycoproteins consisting of a cytotoxic A-chain of 254 amino acids and a B-chain of 264 amino acids. Both chains exert anticancer effects through distinct mechanisms. The A-chain inhibits protein synthesis in ribosomes and promotes apoptosis, whereas the B-chain enhances cytokine secretion and natural killer cell activity.(2) Additionally, mistletoe lectins down-regulate cyclins and cyclin-dependent protein kinases, which results in the arrest of the cell cycle.(1) While mediating these changes, mistletoe extract also critically appears to spare normal cells from degradation.(9) This selectivity compares favorably with immune checkpoint inhibitor therapies, whose use can lead to a panoply of treatment-related adverse events like inflammatory arthritis, myositis, vasculitis, and alveolitis.(10) Such effects may, in part, explain increasing interest among clinicians and researchers in complementary, natural medicines in oncology management.(9) In this setting, mistletoe boasts an 80-year history of use and remains popular as an adjuvant therapy in many European countries.(10)

Despite this longstanding history, mistletoe therapy is highly controversial because of mixed results obtained from studies assessing its abil