Studies suggest that a growing number of cancer patients supplement their treatment with alternative remedies, and Essiac is high on the list.
In a study at the M.D. Anderson Cancer Center in Texas, 4.9 percent of participants said they used the tea in addition to their traditional treatment.
In a similar study at the Mayo Clinic Comprehensive Cancer Center, nearly 10 percent of cancer patients involved in a chemotherapy trial said they were using Essiac as well.
Only one Canadian company can use the trademarked name Essiac, but a four-herb formula for the tea has been widely published in books and on the Internet. It typically can be found in natural food stores such as Wild Oats and Whole Foods. Vitamin stores often carry one or more brands of the tea.
Although Essiac has at least an 80-year history, there have been only a few controlled studies of its effects, and their results have not conclusively proved or disproved the claims of proponents and users that the herbal mixture works as a detoxifier and natural immune stimulant.
Recent research has found some evidence that the tea can inhibit cancer growth in certain kinds of cancer in cell cultures, one animal study suggested that certain kinds of estrogen-positive cancers, including some breast cancers, might get worse when treated with one brand of Essiac. Scientists are hindered by the fact that they do not understand how the human body metabolizes the substance. The concentrations that cause an effect in a test tube may be higher than what a person taking the recommended dose of the tea actually consumes.