Expert panel reviews strategies for nutrition and cancer care
Expert panel reviews strategies for nutrition and cancer care
CHICAGO—Biology and biography were the buzzwords at a panel convened on cancer nutrition at the 2009 Nutrition and Health Conference: State of the Science and Clinical Applications. Panel members offered a primer on the various nutrition strategies that are available to cancer patients.
“The traditional sphere of inquiry is pathology, focusing on disease and prescription,” said Keith Block, MD. “It’s equally important to look at diet and lifestyle factors,” which Dr. Block called biography, and also what he termed “biology,” or an individual’s biochemical terrain.
The interplay of cancer treatment and nutrition can then be approached in an integrated and meaningful way. In addition, “the use of integrative therapies, including the use of tailored antioxidant treatments, can reduce toxicity, leading to completed chemotherapy treatments,” Dr. Block said.
The panel members were:
• Donald Abrams, MD, chief, hematology-oncology, San Francisco General Hospital and director of clinical programs at University of California, San Francisco Osher Center for Integrative Medicine.
• Dr. Block, medical director of the Block Medical Center and Institute for Integrative Cancer Care in Evanston, Ill.
• Cynthia Thomson, PhD, RD, associate professor, nutrition science, medicine, and public health, at the Arizona Cancer Center, University of Arizona College of Medicine in Tucson.
When cancer patients present at his center, Dr. Block said he looks at “oxidation, inflammation, immune competence, and stress chemistry, among other elements.” Antioxidant treatments can mitigate oxidative damage and improve life quality, he said. “If the level of oxidative stress is high in a patient while that patient is on chemotherapy, the efficacy of the chemotherapy has been documented to diminish, leading to a more aggressive cancer and increased toxicity,” he explained.
Dr. Block shared a case of a 60-year-old female non-small-cell lung cancer patient with hepatic and brain metastases. The patient had a 20-year history of smoking. During the course of standard chemotherapy, her therapy at Dr. Block’s clinic included broad-spectrum antioxidant treatment and anti-inflammatory agents, which led to an increase in lycopene levels and the elevation of her total oxidative protection index to above normal.
“We have found that antioxidants have enhanced treatment outcomes, increased survival times, and/or tumor response in our patients,” Dr. Block said. “The majority of clinical studies have shown that antioxidant treatment decreased toxicities.” In addition, Dr. Block said that no clinical trials have uncovered any significant decrease in chemotherapy treatment efficacy as a result of concurrent antioxidant treatment.
He emphasized that generic models of complementary and alternative medicine (CAM) “that aren’t integrated don’t have the (appropriate) impact. The ability to take a more multitargeted, multidimensional approach, I believe, has a significant impact. Diagnosis, life crisis, biochemical elements, clinical elements, and therapeutic impact are all important for clinicians to consider.”
Betting on beta-glucans
Medicinal mushrooms have been a staple in China, Japan, and Korea for centuries, said Dr. Abrams. He explained that the core medicinal value of mushrooms can be found in the beta-glucans, resembling molecules on bacterial cell walls that, when ingested into macrophages, mobilize the immune response. Beta-glucans stimulate cytokines active in tumor inhibition (IFN-γ, TNF-α, IL-2, and IL-12). Differently branched glucans from other mushroom species stimulate cytotoxic T cells, natural killer cells, or other immune cells.
Mushroom-based therapy is most beneficial when used in conjunction with chemotherapy, Dr. Abrams said. Interaction with chemotherapeutic agents is a concern, although mushrooms are used quite widely and safely in Asia. The turkey-tail mushroom (Trametes versicolor) has yielded two proteoglycans: polysaccharide peptide (PSP) from the fungus, and polysaccharide-K (PSK). The latter is marketed in Japan as Krestin, and, according to research done in that country, 262 gastric patients treated with PSK as an adjunct to chemotherapy showed a decrease in cancer recurrence and a significant increase in disease-free survival (Lancet 343:1122-1126, 1994).
Ganoderma lucidum, known as reishi in Japan and Ling Zhi in China, is the source of ganoderic acid triterpenoids, which are thought to inhibit the growth of tumor cells. At UCSF, two patients with hepatitis-B related hepatocellular carcinoma were reported to have significant responses to an imported reishi spore product. A clinical trial is being planned to further investigate, Dr. Abrams noted.
Are mushrooms, with their nonspecific immune enhancing effects, safest to use in patients with immune-related cancers? Other questions about mushroom-based therapy remain. Hopefully some answers may be forthcoming at the upcoming Society for Integrative Oncology meeting in New York in November, he added. “Human clinical trials are important but difficult to do,” Dr. Abrams said, explaining why relatively few trials have taken place involving mushrooms as therapeutics. “But I do think we need to do them.”
The cancer community has seen a steady rise in survivorship, especially in breast cancer, Dr. Thomson said. “While much of that progress is related to drug therapy in relation to estrogen-related cancers, we are also seeing a healthy survivor cohort—a group of women who have adopted a healthier lifestyle, including nutrition and exercise, that has certainly contributed to their overall health.”
Dr. Thomson emphasized that there are no “magic foods.” Instead, patients are encouraged to strive for well-rounded diets. “I want to drive home the importance of variety.”
The Women’s Healthy Eating and Living Study was a randomized trial of 3088 subjects that evaluated the effect of a plant-based dietary pattern on additional breast cancer events and survival. “We looked at oxidative stress,” said Dr. Thomson, who was one of the study coauthors. “And among women with higher levels of beta carotene and alpha carotene and total carotenoids in their blood, we did see a reduction in oxidative stress levels.” (Controlled Clinical Trials 23:728-756, 2002; Cancer Epidemiol Biomarkers Prev 18:484-494, 2009).
An area that requires further study is metabolic syndrome in breast cancer survivors. “We were amazed at the presence of metabolic syndrome in breast cancer survivors: 53%,” she said. “We need to use dietary interventions to enhance their health.”
Dr. Thomson said the best recommendations are for daily exercise and a significant vegetable intake. “I’m a proponent of total cruciferous vegetables. One study indicated that a lower-fat diet helped protect women from estrogen-related tumors. In addition, even a modest amount of weight loss can make a huge difference in terms of metabolic syndrome and cancer recurrence risk” (J Clin Oncol 25:2345-2351, 2007).
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