Essiac: Burdock (Arctium lappa), rhubarb (Rheum palmatum), sheep sorrel (Rumex acetosella), and slippery elm (Ulmus rubra). Flor-Essence: Essiac, red clover (Trifolium pratense), blessed thistle (Carduus benedictus), kelp (Laminaria digitata), and watercress (Nasturtium officinale).
BACKGROUND: Essiac, a botanical formulation of four herbs, was popularized as a cancer treatment in the 1920s by Rene Caisse, a Canadian nurse (Essiac is Caisse spelled backwards). It is believed that she obtained the formula from a patient who claimed to have learned about it from an Ojibwa healer, and who said that the mixture had cured her breast cancer. Caisse began to use the formula in the form of tea and as an injection to treat cancer patients. However, concerns about the use of Essiac led to an investigation by the Cancer Commission of Ontario in 1938, which failed to find evidence of Essiac’s effectiveness. However, Caisse continued to offer it to patients and modified the original product to further promote its use by adding four more herbs. The new formula, Flor-Essence, was thought to be more potent than Essiac, had improved taste, and could be taken orally by patients, thereby eliminating the need for injection.
For additional information, visit the Memorial Sloan-Kettering Cancer Center Integrative Medicine Service website, "About Herbs," at http://www.mskcc.org/AboutHerbs.
During the 1970s and 80s, several researchers in Canada and in the United States, including those at the National Cancer Institute, studied Essiac. All failed to find any evidence of effectiveness.
Despite unsubstantiated claims, Essiac remains a popular anticancer therapy today. Essiac and its variant Flor-essence are manufactured by various companies and marketed worldwide in the form of powders, capsules, teas, and liquid extracts. Promoters claim these products reduce tumor burden, enhance immune response, relieve pain, reduce toxic effects of chemotherapy, and improve survival.
RESEARCH: In vitro studies show that Essiac has antioxidant and cytotoxic properties[2,3]; however, it also stimulated growth of human breast cancer cells. Studies of its antiproliferative effects on prostate cancer cells also yielded conflicting results.[5,6]
Remission of hormone-refractory prostate cancer was reported in one patient, but a retrospective study of breast cancer patients found that Essiac did not improve quality of life or mood.
ADVERSE REACTIONS: A 59-year-old woman reported symptoms of anorexia, nausea, myalgia, fatigue, and generalized abdominal pain following consumption of Essiac over a 6-month period; her symptoms resolved after discontinuing the tea. The manufacturer of Flor-Essence states that users may experience increased bowel movements, frequent urination, swollen glands, skin blemishes, flu-like symptoms, or slight headaches.
HERB-DRUG INTERACTIONS: Decreased clearance of an experimental chemotherapy drug was reported in a patient taking Essiac. This may have been due to inhibition of several cytochrome P450 enzymes by Essiac.