Two published case reports describe the use of milk thistle as either a treatment or an adjunctive therapy in individuals with cancer. One case report describes the use of milk thistle in a 34-year-old woman with promyelocytic leukemia. The investigators administered 800 mg of silymarin during the patient's maintenance therapy, which consisted of treatment with methotrexate and 6-mercaptopurine. During the 4 months of treatment with silymarin, the patient who previously required intermittent breaks in therapy due to abnormal liver enzyme levels had normal liver enzyme levels with no further interruption of therapy. A second case report describes a 52-year-old man with hepatocellular carcinoma. The patient began taking 450 mg of silymarin per day, and spontaneous regression of the tumor was reported in the absence of initiation of anticancer therapy.
In a double-blind, placebo-controlled trial, 50 children who were undergoing treatment for acute lymphoblastic leukemia and who had chemotherapy -related hepatotoxicity were randomly assigned to receive silymarin or placebo for a 4-week period. Four weeks following completion of the intervention, the silymarin group had a significantly lower aspartate aminotransferase (AST) (P = .05) and a trend towards a significantly lower alanine aminotransferase (ALT) (P = .07). Fewer chemotherapy dose reductions were observed in the silymarin group compared to the placebo group; however, the difference was not significant. No adverse events were reported.
Most clinical trials of milk thistle have been conducted in patients with either hepatitis or cirrhosis. Other studies have investigated milk thistle in patients with hyperlipidemia, diabetes, and Amanita phalloides mushroom poisoning. Ten randomized trials [3,4,5,6,7,8,9,10,11,12] have been reported in patients with hepatitis or cirrhosis, and one randomized trial has reported the use of silymarin as a prophylaxis to iatrogenic hepatic toxicity.Endpoints for these trials have included serum levels of bilirubin and/or the liver enzymes AST and ALT, as higher levels are an indicator of liver inflammation, damage, or disease. The lowering of these serum levels is a sign of an improving condition. In patients with hepatitis A and B, one clinical trial found silymarin (140 mg daily for 3-4 weeks) resulting in lower levels of AST, ALT, and bilirubin by day 5, compared with a placebo group. In another randomized, placebo-controlled study of patients with viral hepatitis B, silymarin (210 mg daily) had no effect on course of disease or enzyme levels.