I have read claims that dandelion root tea can stop cancer cells from spreading. Have there been any studies related to the effectiveness of dandelion root extract on certain types of cancer?

Answer:

No, there are no clinical studies in people showing that dandelion root extract or tea helps treat any type of cancer. A study was approved in Canada in 2012 to evaluate dandelion root extract for blood cancers resistant to treatment, but that trial did not take place. The principal investigator for that trial, Caroline Hamm, MD, had published an earlier case report of a 70-year-old man with acute myelomonocytic leukemia resistant to chemotherapy who "responded" to dandelion root tea based on a normalization of his complete blood count (a blood test that measures levels of blood cells that can be harmed by cancer or cancer treatment) after about 2 years (Hamm, Blood 2011). Two years later (i.e., four years after diagnosis), the patient reportedly still remained in remission as long as he drank at least three cups per day of dandelion root tea. Three other cases of using the tea in patients with blood cancers were reported, although death or relapse occurred in two of these cases (Hamm, Blood 2013). Dr. Hamm was quoted in 2017 as being firmly against people considering dandelion root, which she described as offering "false hope," in place of standard cancer therapy.