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.[1-6] It is not clear whether the described patient populations consisted entirely of adults or whether they included children.
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.[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 received permission to conduct studies on the safety and the efficacy of Essiac in cancer patients.[2,4-7] 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). At that time, the available incomplete data were reviewed, and no clear evidence of improved survival could be demonstrated for treated patients.[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. 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. 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 obtained Essiac under Canada’s Emergency Drug Release Program between 1978 and 1982.[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. The Bureau found 47 patients who did not benefit from Essiac; 1 had subjective improvement, 5 required fewer analgesics, 4 had an objective response, and four were in stable condition.[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.[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.
No results of human studies of Flor Essence have been reported anecdotally or in the peer-reviewed scientific literature.
- Tamayo C: Essiac for cancer. Alternative Therapies in Women's Health 2 (3): 19-23, 2000.
- Kaegi E: Unconventional therapies for cancer: 1. Essiac. The Task Force on Alternative Therapies of the Canadian Breast Cancer Research Initiative. CMAJ 158 (7): 897-902, 1998. [PUBMED Abstract]
- Locock RA: Essiac. Can Pharm J 130: 18-9, 1997.
- Herbal treatments. In: US Congress, Office of Technology Assessment: Unconventional Cancer Treatments. Washington, DC: U.S. Government Printing Office, 1990. OTA-H-405, pp 71-5. Also available online. Last accessed December 17, 2014.
- Essiac. Toronto, Canada: Canadian Breast Cancer Research Alliance, 1996.
- LeMoine L: Essiac: an historical perspective. Can Oncol Nurs J 7 (4): 216-21, 1997. [PUBMED Abstract]
- Campbell MJ, Hamilton B, Shoemaker M, et al.: Antiproliferative activity of Chinese medicinal herbs on breast cancer cells in vitro. Anticancer Res 22 (6C): 3843-52, 2002 Nov-Dec. [PUBMED Abstract]