Milk Thistle Treats Chemotherapy-Induced Hepatoxicity

Nancy Fowler Larson

December 14, 2009

December 14, 2009 — Hepatoxicity caused by chemotherapy can be successfully treated with milk thistle (MT), according to a study of children with acute lymphoblastic leukemia (ALL) published online December 14 in Cancer.

"Currently, there are no substitute chemotherapy agents that provide the same effectiveness against ALL yet preserve liver function. There are also no hepatoprotective medications that allow chemotherapy to continue to be administered while preserving liver function," write Kara M. Kelly, MD, from the pediatric oncology department at Columbia University Medical Center, New York City, and colleagues. "Thus, adjunctive agents that may enable optimal doses of chemotherapy to be administered without necessitating a decrease in the recommended doses of chemotherapy are of clinical significance and may further improve survival in children with ALL."

Earlier studies have shown that MT reduces liver damage caused by cirrhosis or ingested toxins. The goal of this MT evaluation was to determine whether the herb can safely and effectively remedy chemotherapy-induced liver inflammation — a common adverse effect that can necessitate reduction or suspension of the cancer treatment.

The randomized controlled, double-blind study consisted of 50 children with ALL who were in the maintenance phase of therapy and had a hepatic toxicity of grade 2 or greater on amino alanine transferase (ALT), aspartate amino transferase (AST), or total bilirubin (TB) levels.

For a period of 28 days, patients received either MT (5.1 mg/kg/day) or a placebo. Patient visits and reports and chart reviews were used to monitor the safety of MT. Liver inflammation was determined by blood level increases of AST and ALT.

On day 28, there were no noteworthy alterations in mean ALT, AST, or TB levels. However, the authors write, "at day 56, the MT group had a significantly lower AST (P = .05) and a trend toward a significantly lower ALT (P = .07)." Ingesting MT seemed to produce no negative effects, and the herb did not reduce the effectiveness of chemotherapy. Furthermore, patients taking MT were more likely to maintain their prescribed chemotherapy dosages.

"Although not significantly different, chemotherapy doses were reduced in 61% of the MT group compared with 72% of the placebo group. In vitro experiments revealed no antagonistic interactions between MT and vincristine or L-asparaginase in CCRF-CEM cells," the authors write.

The study authors noted that their research was made stronger by product quality analysis, stability testing, and a goal of quantifying plasma levels of silibinin. They also reported several limitations. These included the study's small sample size and an MT dose that may have been smaller than necessary. They also acknowledged that those taking MT had a rate of compliance that was appreciably lower than that of the placebo group. Overall, however, they hailed their findings as an important step toward using MT to treat hepatotoxicity in cancer patients.

"Despite our study's limitations, it provides preliminary evidence that MT may be a safe, effective, supportive-care agent," the authors write. "Future investigations are needed to determine the appropriate dose and duration and to identify populations that may gain the largest clinical benefit."

The American Institute for Cancer Research, the Tamarind Foundation, and the National Cancer Institute supported this study. The study authors have disclosed no relevant financial relationships.

Cancer. Published online December 14, 2009.

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