Alternative and complementary nutritional therapies in cancer prevention and treatment: implications in clinical practice

P revalence of use of complementary and alternative nutritional therapies is steadily increasing in industrial nations, where an estimated 25–50% of the population use some form of these therapies for minor ailments and major disease treatment and prevention.1 An estimated 100 million Americans now use nutritional dietary supplements on a regular basis and the number is growing. Gross domestic revenues for the supplement industry have mushroomed to nearly $10 billion dollars in annual sales. Products include vitamins, herbs, amino acids, and other natural products and their derivatives. Treatment of cancer continues to present a clear physical and emotional challenge to the patient and the health professional. A significant number of patients are seeking alternative and complementary therapies. Studies examining the prevalence of use of alternative and complementary therapies in cancer have reported widely different statistics based on the type, length of time since diagnosis, and stage of the disease. Surveys have reported that 80% of patients with breast cancer2 and 25% of those with headand-neck cancer had tried some form of alternative therapy.3 In two groups of patients with prostate cancer,4 27.4% and 38.9% used some form of complementary therapies. Approximately 46% of children with cancer were reported to have used at least one alternative or complementary therapy, with fewer than 50% reporting this use to their physicians.1 Patients with stage IV disease have reported using alternative therapies more frequently than patients with less severe diagnoses. Several terms have been adopted to describe non-traditional practices, so it may be important to make a distinction between alternative and complementary therapies. The term complementary/integrative therapies refers to therapies provided as an adjunct to mainstream medicine and are intended to provide symptom control, enhance quality of life, and/or empower clients. Complementary/ integrative therapies may represent a desired addition and balance to technologically sophisticated cancer care. The term alternative therapies refers to therapies that are independent of surgery, radiation, and chemotherapy. Most of these therapies are unproven and they may in some cases present a direct danger as a result of inherent toxicities, and patients who use them may suffer adverse consequences due to delays in receiving effective conventional therapies. Although a vast majority of individuals appear to use unconventional therapies in conjunction with, rather than instead of, conventional treatments,5 4.4% of the people reported relied primarily on alternative therapies. The role for nutrients in cancer prevention and treatment has also been the topic of much interest in the scientific and lay press. The concept of prevention of cancer using nutrients is based on evidence from human epidemiology, a few clinical trials, and studies of animal carcinogenesis models for cancer-inhibiting potential of these nutrients and non-nutrients derived from foods. Basic research has identified nutrients as agents that are carcinogen blocking, antioxidant or antiinflammatory, inhibiting mutagenesis and hyperproliferation, as well as those that induce apoptosis or differentiation as critical characteristics for chemoprevention regardless of their specific molecular targets. More than 40 diet-derived agents and agent combinations have been identified and are currently being evaluated clinically as chemopreventive agents for major cancer targets including breast, prostate, colon, and lung. Some of the most promising nutrients identified as chemopreventive agents include soy isoflavones, greenand black-tea polyphenols, curcumin, lycopene, indole-3carbinol, vitamins D and E, selenium, and calcium. It is possible that interventions with nutrients will prevent, delay, or reverse the process of carcinogenesis and thus reduce the incidence of and mortality due to human cancers. Several phase II clinical trials have been initiated with the intent to evaluate the efficacy of these agents in altering standardized and validated surrogate endpoints for cancer. Preliminary results of these studies are promising and have raised interest in this strategy for cancer prevention. Conclusive evidence can only be obtained from well-characterized agents in suitable cohorts using reliable intermediate biomarkers of cancer for evaluating their efficacy. Experimental and epidemiologic data must prove efficacy, and the biologic and mechanistic plausibilities of each nutrient’s action must be unequivocally shown. In addition, if these agents are to be used in humans for long periods, their safety during chronic administration and interaction with other traditional therapies must be explored before they become incorporated into standard therapy protocols.6 The use of alternative medicine as a frontline therapy also frequently causes a patient to delay seeking conventional, proven, and effective treatment such as surgery. There are times when such a delay can mean the difference between life and death. Certain alternative therapies can produce a decreased quality of life; the use of coffee enemas is but one example. Direct physical harm as a result of toxicities and interference with proven treatments are of significant concern to practitioners, especially when patients do not inform their health professionals about use of alternative/ complementary therapy. In addition to posing a financial burden to patients and their families, it has been reported that new users of unconventional cancer treatments are more depressed and suffer severe somatic symptoms in addition to having greater fears than non-users that their cancers may recur.2 It is extremely critical for practitioners to await the results of empirical research that clearly demonstrates the efficacy of the nutrients before recommending supplemental doses above those required to prevent deficiency for cancer prevention or treatment. It is important for practitioners to identify patients who are vulnerable and support patients in making informed, safe, and appropriate choices. It has become imperative for the health professional to develop a greater awareness of the alternative and complementary therapies that are available and their efficacy in treatment and prevention. It is our duty not only to provide the best in conventional care but also to provide accurate information and guidance with regard to alternative and complementary therapies for cancer treatment and prevention. Correspondence to: Patricia A. Burns, PhD, RN, FAAN, Dean and Professor, College of Nursing, University of South Florida, 12901 Bruce B. Downs Boulevard, MDC Box 22, Tampa, FL 33612-4766, USA. E-mail: pburns@hsc.usf.edu