As more and more cancer patients turn to complementary and alternative medicine (CAM) therapies, their physicians face the challenge of keeping up with trends in CAM use and the evidence for the potential benefits and harms of these treatments.
To help doctors and their patients make decisions about which CAM therapies to use and which to avoid, experts have begun to create databases and strategies for evaluating the treatments. For an area in which new therapies are constantly going in and out of fashion, this is proving to be no small task.
A team led by researchers at the Osher Institute of Harvard Medical School in Boston recently published a wide-ranging review of CAM therapies for cancer and laid out a framework for assessing the merits of others that may surface in the future. It shows that, although CAM research has matured in recent years to the point where some useful recommendations can be made, the questions still far outnumber the answers.
The idea was to present "specific criteria to characterize the interventions into one of three categories: those for which there is sufficient evidence to view the therapy as reasonable and, in some circumstances, worthy of recommendation; those that are reasonable with caveats; or those that are clearly not wise choices," said David Eisenberg, M.D., director of the Osher Institute and Division for Research and Education in Complementary and Integrative Medical Therapies, and senior author on the recent article, which was published Dec. 3 in the Annals of Internal Medicine. "Its a road map designed to give direction toward informed decision-making."
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The groups approach emphasizes safety over efficacyor the lack thereof. Therapies are not discouraged unless either major safety concerns exist, or two or more randomized clinical trials have been done and at least two-thirds of trials suggest the therapy is ineffective. Thus, they advise physicians to accept patients use of shark cartilage despite acknowledging that current evidence does not support its efficacy against cancer and that the usual oral or rectal routes of administration are unlikely to allow the antiangiogenic proteinsthe putative active agentsto enter the circulatory system.
Among therapies intended to affect disease progression and survival, the only one to receive even a tentative thumbs-up from the authors is vitamin E for latent prostate cancer. The group advises doctors to accept, monitor, and possibly consider recommending the vitamin for some patients. Several palliative therapies, including massage for anxiety and acupuncture for chemotherapy-related nausea, also receive this grade. None of the therapies get an unequivocal recommendation, in part because safety concerns vary among patients.
"Even if a therapy is safe for many patients, there can be certain subgroups of patients in whom that therapy is riskier, and therefore contraindicated," Weiger said. Several of the contraindicationsfor soy, vitamins C and E, acupuncture, and deep massageare related to the risk of bleeding. Others involve the risk of malnutrition with dietary regimens, the possible estrogenic effects of soy isoflavonoids in breast cancer, and the potential for antioxidants and other supplements to interfere with chemotherapy and radiotherapy.
Radiation and many chemotherapy drugs produce free radicals, which cause toxic side effects but may also be important in mediating anticancer effects. When cancer patients take antioxidants that limit free radical toxicity, Weiger said, they might be undermining therapeutic effects of chemotherapy or radiation treatment. The limited studies to date have produced mixed results, suggesting that antioxidants may either diminish or boost chemotherapy effectiveness.
"Right now, we dont know which combinations of antioxidants and conventional agents are safe and which are not," she said. "They are just going to have to be tested on an individual basis." She added that the structure they developed and published in the recent Annals article will help physicians and patients use the available evidence and information to make decisions about CAM therapies.
"This is an area full of fads," said Barrie Cassileth, Ph.D., chief of the Integrative Medicine Service at Memorial Sloan-Kettering Cancer Center in New York and author of The Alternative Medicine Handbook. "What is popular today may not be popular in 6 months."
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"In addition to the biological harm they can do, these unproven remedies may prevent patients from getting care in a timely fashion," Cassileth said, adding that her own research suggests that 8% to 10% of cancer patients seek alternative treatments before, or instead of, mainstream medical treatment.
Andrew Vickers, Ph.D., a research methodologist and biostatistician at Memorial Sloan-Ketterings Integrative Medicine Service, is the author of a module on CAM therapies for cancer patients on the American College of Physicians-American Society of Internal Medicines Web site. He recommends that physicians dissuade patients from using unproven therapies that have substantial risk of adverse events. He also provides general guidelines to discourage treatments that are promoted as alternatives to conventional care or that would incur significant travel or financial cost (in recognition that some patients cross international borders to get treatments unavailable at home).
"Doctors and other people giving advice need to be extremely clear about possible harm," he said. "To travel to Mexico in the last weeks of life and take an unproven therapy could cause clinical, economic, and emotional harm," he said.
Physicians and patients looking for detailed advice on natural products used in treating cancer have a new resource in Memorial Sloan-Ketterings database about herbs, botanical, vitamins and other remedies (www.mskcc.org/aboutherbs), which debuted online in November. Intended primarily for oncologists, it is publicly accessible at no cost and contains detailed entries more than 130 herbs and other "natural" cancer therapies.
Each referenced entry includes a clinical summary and information on food sources, pharmacokinetics, mechanism of action, adverse reactions, and potential drug and laboratory test interactions. Contents are determined by the agents that patients use. As new products come to the attention of the centers doctors, staff at the center will research and write new entries for the database, said Cassileth. A version of the database geared for patients will be added to this Web site in February 2003, she added.
Thus far, Memorial Sloan-Ketterings herbal information is mostly cautionary. The centers policy is that herbal remedies and other dietary supplements cannot be administered to patients outside clinical trials because of concerns over adulteration, misbranding, and lack of regulation.
Despite the obstacles, Cassileth said, "Some of these botanicals have great potential to be useful in cancer medicine." Memorial Sloan-Kettering has six ongoing trials of herbal products, but they do not use the preparations sold over the counter in U.S. health food stores. Instead, the products are either imported from Japan, where herbal medicines are subject to the same rigorous quality control as other drugs, or they are imported as raw herbs or botanical products from China and tested for contamination, consistency, and stability as would a potential pharmaceutical agent.
Although there is much to be learned about herbal medicines, "We know infinitely more today than we did even five years ago," Cassileth said.
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