About Cancer

Something about antioxidants could be putting cancer patients at risk - but it's not the supplements themselves. Instead, it's the lack of knowledge about how they may help fight malignancies that is the real danger, says cancer expert Keith Block. A report recently published in the American Cancer Society's medical journal, CA, suggests cancer patients could be reducing the effectiveness of radiation and chemotherapy treatments by taking antioxidants. In fact, the article states, supplements might actually be "feeding" their tumors and even reduce their chance of a cure. Dr. Block points out, however, that the author of the article, Gabriella M. D'Andrea, MD, of Memorial Sloan Kettering Cancer Center based her conclusions on a review of a handful of human trials that showed supplements often don't benefit cancer patients and could cause them harm.

"The article ignored a growing body of published research that shows just the opposite. In fact, there is compelling data that the cautious and judicious use of a number of antioxidants can be helpful in the treatment of cancer, either as 'stand alone' agents or as additions to standard chemotherapy and radiotherapy," says Dr. Block, Clinical Assistant Professor at the University of Illinois College of Medicine at Chicago.

According to the American Cancer Society (ACS), more than 1,500 Americans die from cancer each day. For advanced metastatic cancers, the prognosis is typically between one and two years. "Chemotherapy can improve survival for many of these individuals, but this often comes at the expense of toxic side effects that can at times be more frightening than the disease itself. However, some physicians have found that patients who receive antioxidant-rich nutrition experience fewer side effects during and after chemotherapy. Many also believe that treatment response and survival are also improved," Dr. Block notes.

There is a growing body of scientific research to back this up, including the gold standard of evidence-based medicine -- randomized controlled clinical trials. "Glutathione has been shown to significantly reduce the various toxic effects of cisplatin and other chemotherapy drugs in six randomized controlled clinical trials to date. Not one of these studies found any sign of interference between glutathione and the various chemotherapy drugs," Dr. Block says. He adds that studies of the potent antioxidant called melatonin have been even more favorable, including multiple studies showing significant improvements in both outcome and survival in advanced cancer patients undergoing chemotherapy.

The numbers of studies showing positive results of cancer therapies supplemented with antioxidants is far larger once non-randomized studies are included. "Although those trials are not considered the gold standard for medical evidence, it's worth noting that virtually all of them suggest favorable outcomes or at least no interference with chemotherapy," says Dr. Block.

So where does the idea come from that supplements could be harmful to cancer patients? Dr. Block explains that some chemotherapy agents create free radicals or similar molecules called reactive oxygen species (ROS). ROS are highly reactive and unstable forms of oxygen that have the capacity to damage genes and other cell structures. These in turn cause the intended cellular damage to cancer cells. Because antioxidants are used to counteract the damaging effects of ROS, some researchers assume concurrent use of antioxidants should limit the effectiveness of chemotherapy drugs that rely on ROS and may advise against the use of antioxidants with all chemotherapy agents, regardless of whether or not they create ROS.

"This is a speculative theory," says Dr. Block. "In fact, other cancer researchers like myself work from the premise that cancer and many anticancer treatments can result in the increased production of free radicals and ROS that tend to fuel the progression of the cancer. In other words, oxidation promotes malignant progression and drives a cancer cell to become even more aggressive. This helps explain why numerous antioxidants have been shown to slow the growth and spread of cancer. Some scientists think that the ROS produced by chemotherapy drugs may actually hinder the effectiveness of the drugs themselves."

Dr. Block says both sides of the antioxidants-in-cancer-therapy debate can agree on one point: more research is needed to find out how to best use supplements to help fight cancer. "However, I take issue with physicians who say that patients should be advised against taking antioxidant supplements because not enough evidence exists to support their efficacy," he states. "Patients certainly should not indiscriminately take antioxidants in hopes that they will be helpful; they need to consult with practitioners who are experienced in this area before choosing to use antioxidant supplements with chemotherapy. I believe, in particular, that people who face a late stage, more advanced or life-threatening cancer should use every tool at their disposal to prolong survival, under the guidance of physicians who are open to the use of supplements and who have worked with patients in this situation. For the moment, the bulk of the evidence supports the use of antioxidants with the cancer patient. Until well designed studies actually show a real interference, I will continue to urge patients to use supplements that appear to have the ideal composition for combating cancer, improving the ability to better tolerate treatment and for supporting the treatments these patients receive." Dr. Block is Medical/Scientific Director of the Block Center for Integrative Cancer Care and Optimal Health.

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The Block Center for Integrative Cancer Care and Optimal Health, located in Evanston, Illinois, was founded in 1980 by Penny and Keith Block, M.D. with a focus on treating the patient as a whole person, not treating just the diagnosis or symptoms. The Center's research-based treatment integrates an innovative approach to the best of conventional medicine with scientifically sound complementary therapies -- therapeutic nutrition, botanical and phytonutrient supplementation, prescriptive exercise, and systematic mind-body strategies -- to enhance the recovery process. Block has pioneered this "middle ground" approach to cancer care and optimal health - designing a total treatment plan that is tailored to the precise needs of each patient, using a unique set of clinical and laboratory assessments. The Block Center is breaking new ground with the creation and development of Cancer Rehab as an innovative treatment modality, and is currently the only private North American medical center using chronomodulated chemotherapy. While the Block Center is a full treatment clinic, it is involved in clinical cancer research with other university facilities in the United States and Israel (www.blockmd.com).