No report of a clinical study of Essiac has been published in the peer-reviewed scientific literature. Brief descriptions of one incomplete clinical study and one retrospective evaluation of Essiac as a treatment for cancer have been published. Reviewed in [1,2,3,4,5,6] It is not clear whether the described patient populations consisted entirely of adults or whether they included children.
Essiac and Flor Essence are herbal tea mixtures that are sold worldwide as health tonics or herbal dietary supplements (see Question 1).
Essiac was first promoted as a cancer treatment in the 1920s. Flor Essence was created a number of years later (see Question 2).
Supporters of Essiac and Flor Essence say that these products make the immune system stronger, have anti-inflammatory effects, and show anticancer activity (see Question 3).
Laboratory, animal, and clinical (human) studies...
As noted previously (refer to the History section of this summary for more information), the developer provided a four-herb recipe for Essiac to a Canadian corporation in 1977. Reviewed in [2,6] In 1978, the corporation filed a preclinical new drug submission with the Canadian Department of National Health and Welfare (Health Protection Branch) and was given permission to conduct studies on the safety and the efficacy of Essiac in cancer patients. Reviewed in [2,4,5,6,7,8] In 1982, the Department withdrew its permission after determining the research was not being conducted as planned (refer to the History section of this summary for more information). Reviewed in [2,4,5,6,7,8] At that time, the available incomplete data were reviewed, and no clear evidence of improved survival could be demonstrated for treated patients. Reviewed in [1,2,5,6] Pain control and quality of life were not assessed in these studies. The review of the data indicated, however, that Essiac was not toxic. Reviewed in [5,6] Because no evidence of harm was found, the Canadian government allowed the corporation to distribute Essiac to cancer patients through their physicians under Canada's Emergency Drug Release Program. Nonetheless, restrictions were imposed on the promotion of Essiac as a treatment for cancer. Reviewed in  Access to Essiac under Canada's Emergency Drug Release Program has since been discontinued.
In the early 1980s, the Canadian Department of National Health and Welfare (Bureau of Human Prescription Drugs) conducted a retrospective review of data voluntarily submitted by physicians for 86 cancer patients who had gained access to Essiac under Canada's Emergency Drug Release Program during the period between 1978 and 1982. Reviewed in [1,2,4] (Note:  states that data from 87 patients were reviewed.) The Bureau's evaluation was based on written summaries submitted by the physicians and not on a review of the original patient records. Reviewed in  The Bureau found 47 patients did not benefit from Essiac; one had subjective improvement, five required fewer analgesics, four had an objective response, and four were in stable condition. Reviewed in [1,4] Among the remaining 25 patients, 17 had died, and the reports for 8 were considered unevaluable. The Bureau solicited additional information about the four patients who had an objective response and the four patients who were in stable condition. This additional information revealed that, among these eight patients, two had died, three had progressive disease, and three remained in stable condition. Reviewed in [1,4] The three patients in stable condition had received previous conventional therapy. Therefore, the benefits of treatment for these patients, if any, could not be clearly ascribed to Essiac. Reviewed in