Study adds confusion on antioxidants during cancer treatment

Published: 10/20/2008 12:03 AM

One of the most controversial areas in cancer treatment is the use of antioxidants during chemotherapy or radiation therapy. Many clinicians and researchers believe that the use of antioxidants protects cancer cells from the oxidant action of chemotherapy or radiation therapy.

In contrast, the majority of clinical research demonstrates that the judicious use of antioxidants can significantly improve patient outcomes. However, recent research from the Sloan-Kettering Institute published in the medical journal Cancer Research, suggests that vitamin C protects cancer cells from chemotherapeutic agents and that antioxidants such as vitamin C should be avoided during cancer therapy.

In this study, the researchers found that mice fed vitamin C before their chemotherapy actually had faster-growing tumors than mice not fed vitamin C. In the second part of the study, test-tube human cancer cells pretreated with vitamin C before adding chemotherapy had a 30 to 70 percent greater resistance to the chemotherapy agents than human cancer cells not pretreated with vitamin C. The researchers concluded that vitamin C supplementation during chemotherapy might protect cancer cells.

Although this research seems convincing, the researchers made a major mistake in the design of their research and their conclusions.

"Garbage in, garbage out" is an old computer programmer adage that means if the experiment is faulty, the results are worthless. In this study, the researchers did not use vitamin C (ascorbic acid). They used dehydroascorbic acid. Although ascorbic acid and dehydroascorbic acid might sound similar, they are worlds apart, according to Jeanne Drisco, M.D., a professor of orthomolecular medicine and director of the Program in Integrative Medicine at the University of Kansas Medical Center.

All known actions of vitamin C are the result of ascorbic acid - not dehydroascorbic acid. Dehydroascorbic acid actually is somewhat toxic to humans and the human body works very hard to keep blood levels of dehydroascorbic acid at a minimum. According to Dr. Drisco, using dehydroascorbic acid instead of ascorbic acid generates data that is "biologically and clinically irrelevant." Complicating this research is that, unlike humans, mice make their own vitamin C. In vitamin C research, mouse results might not apply to humans.

The goal of clinical research should be to shed light on the unknown and to clarify serious questions. In cancer therapy, it is vitally important that we know if antioxidants help or harm. Sloan Kettering has an international reputation as one of the best cancer centers in the world. Their research is top-notch and they have, without question, helped thousands of patients. However, this recent research with vitamin C has done nothing to clarify the role of antioxidants during chemotherapy and probably has contributed significantly to the ongoing confusion among physicians and patients.

• Dr. Patrick B. Massey M.D, Ph.D., is medical director for complementary and alternative medicine for Alexian Brothers Hospital Network.