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Nutrition and cancer: No magic bullet, but an important aspect of treatment, prevention
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When it comes to nutrition, patients with cancer face a diverse set of challenges. Aggressive treatments can cause chronic loss of appetite and malnutrition; patients may be influenced by reports in the lay press as to what (or what not) to eat, all the while ingesting trendy nutritional supplements and “cures” that can interfere with traditional treatments. Often, hematologists and oncologists are the ones to whom patients turn to for help in sorting through the sometimes conflicting information they receive. Unfortunately, patients are not the only ones who have misconceptions about nutrition and its influence in oncology.
“In some sense, oncologists view nutrition as alternative medicine,” said Lawrence H. Kushi, ScD, associate director for Etiology and Prevention Research at the Kaiser Permanente Northern California Division of Research, Oakland, Calif. “To the extent nutrition is thought about by most clinicians, it has been in the context of ensuring patients receive enough calories so they can withstand the toxic effects of treatment.”
Without a doubt, being healthy enough to withstand treatment is one goal of nutrition therapy. Patients undergoing bone marrow transplant, for example, need to maintain protein stores to minimize side effects of treatment, said Leslie L. Popplewell, MD, FACP, clinical associate professor of hematology/hematopoietic cell transplantation at City of Hope, Duarte, Calif.
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Photo courtesy of Steven Clinton, MD, PhD |
“It can be a cycle that’s hard to break. Poor nutrition can lead to adverse events, which, in turn, lead to loss of appetite or an inability to swallow or chew. That leads back to low energy and to increased adverse events,” Popplewell said.
Veronica McLymont, PhD, RD, director of food and nutrition services at Memorial Sloan-Kettering Cancer Center, said many misconceptions about nutrition and cancer stem from half-truths and misinterpretation of research.
Misinformation can come from both sides, in which patients generalize the results of a single study to all cancer patients or when physicians and/or dietitians do not demand the same, rigorous evidence-based evaluation of nutrition studies as they would of other novel therapies.
According to Kushi, often the media seizes on a piece of information from a clinical study without fully investigating it, and propagates the story long after further studies have invalidated or corrected the information. In one small study, tissue culture studies indicated that ER–positive breast cancer cell lines proliferated when exposed to isoflavones such as those found in soy products. The information was picked up and publicized, Kushi said, but recent studies indicate increasing soy intake results in better outcomes for patients with breast cancer. “I would bet many websites still insist people with ER–positive breast cancer should be concerned about soy,” he said.
Fad diets may also capture a patient’s interest and influence treatment. McLymont defined fad diets as those “based on the restriction of certain foods or taking herbal, megavitamin or pharmaceutical products.” Examples include: detoxification diets, such as the use of coffee enemas; macrobiotic diets; raw food diets; juice diets; or diets limited to organic foods. The inherent problem of a fad diet or focusing on any supervitamin, supermineral or superfood is that to do so ignores the multifactoral nature of cancer.
“It is not one defect or one mutation that causes cancer. In fact, dozens if not hundreds of varieties of cancer exist,” said Steven K. Clinton, MD, PhD, director of genitourinary oncology for the James Cancer Hospital at Ohio State University. “The risk factors or etiologic factors for them are quite diverse.”
HemOnc Today interviewed experts in the field with the intent of clarifying some of the myths surrounding nutrition and patients with cancer. “Friends, family and the media all have something to say to patients with cancer about food and supplement approaches to their disease,” Clinton said. “Some of it is appropriate and reasonable. Other advice may come from companies playing on the profound anxieties and fears of a cancer patient.”
Role of the dietitian
To sift through the maze of health-related messages, said McLymont, it is important for patients with cancer to speak with health care professionals who are knowledgeable about the relationship between nutrition and cancer. That professional may not always be the patient’s oncologist, but a registered dietitian trained in working with oncology patients. “A physician’s training lies in treating the disease. Dietitians are trained in nutrition,” said Stephanie Meyers, MS, RD, LDN, senior coordinating dietitian at Dana-Farber Cancer Institute in Boston. When making referrals for patients, Meyers recommended physicians search for a registered or licensed dietitian, particularly those who are board-certified by the American Dietetic Association as a specialist in oncology nutrition (CSO). To sit for the exam, dietitians must maintain their RD status for 2 years and have documentation of 2,000 hours of practice experience working directly with patients at risk for or diagnosed with malignant or pre-malignant conditions or indirectly through roles in management, education, industry or research linked to oncology nutrition.
When a patient is referred to a dietitian, the first part of the process is typically a nutrition assessment in which its determined whether the patient is experiencing treatment-induced effects such as appetite changes, nausea and constipation or whether he or she is taking nutritional supplements. A dietitian looks for red flags that signal risks for malnutrition and comorbidities, as well as identifying areas where a patient can improve his or her diet, Meyers said.
Besides providing knowledge about general nutrition guidelines and recommendations from organizations such as ACS or American Institute for Cancer Research (AICR), dietitians can tailor those recommendations to individual patients based on patient characteristics, disease, stage of treatment and adverse effects. They will consider patient preferences for food so the patient is more likely to comply with a nutrition plan.
Nutrition counseling also allows discussions about patient concerns and to employ visual education about the amount of food patients should eat. It is also an opportunity to collect information about what dietary changes, including the use of supplements, a patient may be making on his or her own. A nutritionist can then convey the patient’s plan to the oncologist, so that the patient is receiving truly integrated care.
Nutrition and patient psychology
One sentiment shared by the physicians and dietitians who spoke with HemOnc Today was that nutrition was often used by patients as a way to feel in control of their treatment, or was used as a way to find meaning in a cancer diagnosis.
“People want to assign a reason for having cancer. They may blame cancer on nutritional deficiencies or how they ate [pre-diagnosis],” Popplewell said. She cautioned physicians to watch for patients engaging in magical thinking: that they will be able to make and maintain wholesale changes in their diet and that those changes will immediately improve treatment or erase their cancers.
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Physicians also need to be careful about being too dismissive of a patient’s interest in nutrition while providing guidance to ensure they are not pursuing something that could decrease treatment efficacy or create other nutritional imbalances.
“One of the difficulties for clinicians is trying to be positive with patients, encouraging them to do healthy things without tromping on those beliefs too hard,” said Tim Byers, MD, MPH, associate director for cancer prevention and control at the University of Colorado Cancer Center. “Oncologists, radiation therapists, surgeons and others taking care of cancer patients need to project a positive view of the future and encourage patients to rehabilitate, eat healthy foods and be physically active.”
Clinton said when patients give nutrition a reasonable focus, positive outcomes can occur. “When a patient reviews information on nutrition and is able to make some changes in their diets, they gain a wonderful sense of empowerment that they are engaged in the fight along with the clinical team, that everyone is working together for the same goal,” he said.
The challenges of cancer treatment
When it comes to establishing a nutritional plan for patients with cancer, adverse effects of treatment such as gastrointestinal distress, cachexia and loss of appetite can be a huge factor. “Taste changes as a result of treatments can make foods taste like dirt or metal,” Meyers said. “Treatments may lead to dry mouth, which also alters taste and takes away the enjoyment they used to receive from eating.”
For patients who are uninterested in eating, Meyers recommends eating small meals that consist of the equivalent of three-fourths or one-half cup of food every 2 to 3 hours. Drinking 2 oz of a protein shake throughout the day, either commercially available or homemade, can increase a patient’s caloric and protein intake.
To cope with changes in taste, Meyers encourages patients to try foods they used to dislike. “Because they cannot taste things or because their taste expectations have shifted, they may discover a food they previously avoided is now palatable and provides nutrition,” she said. “I have more patients eating beets, kale and tofu than you would imagine.”
Although patients and physicians should be concerned about loss of appetite leading to cachexia, Byers said weight loss is not a concern for the majority of cancer patients. “Obese patients with cancer should not be told to not lose weight,” he said. “Once patients begin to emerge from the tunnel of hearing their initial diagnosis and making it through their first treatment, physicians should also have them concentrate on losing weight and becoming more physically fit.”
This advice, Meyers said, could be due to the fact that, for some patients, fat deposited around the midsection can act like a hormone pump, secreting and producing hormones. “For someone who may be at risk for breast cancer, for example, being overweight and being exposed to hormones can increase their risk for breast cancer,” she said.
In addition, numerous studies have reported links between obesity and cancers of the colon, gallbladder, pancreas, endometrium, breast (in postmenopausal women), prostate and kidney, McLymont said. “In the United States, approximately 85,000 new cancer cases per year are related to obesity,” she said.
To combat obesity, experts, including the ACS, said a healthy diet should be low in refined sugar and processed foods, and rich in fruits, vegetables and whole grains. For further information, physicians can direct patients to websites with credible nutritional guidelines, such as those from the NCI, the AICR, the ACS or caring4cancer.com. The NIH’s Office of Dietary Supplements website also offers evidence-based treatment recommendations for those patients who are utilizing supplements.
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By following the dietary suggestions offered by these organizations and institutions, “the end result for most people is they lose a little bit of weight,” Meyers said. “The question now is whether it’s the weight loss itself that helps lower the risk for cancer [recurrence] or is it the effect of each individual dietary strategy that lowers risk?”
Benefits, dangers behind supplementation
In conjunction with a healthy diet, many patients with cancer self-prescribe nutritional supplements to replenish calories and nutrients lost due to illness and treatment, McLymont said. Although a review of medical literature on nutritional supplements provides evidence both for and against routine supplementation, a common complaint among clinicians is that few nutritional supplements are approved by the FDA, and that many supplements counteract traditional pharmaceutical treatment regimens.
Reports in the mainstream press and anecdotal reports on websites have espoused the benefits of fish oil or other omega-3 supplements to lessen cachexia, probiotics to improve gut integrity and lessen chemotherapy-induced diarrhea, and calcium to decrease the likelihood of recurrent colon polyps. But some studies have found that calcium can increase the risk of prostate cancer, Kushi said. “Do we need a gender-specific recommendation for all women at risk for colorectal cancer to take calcium while men with other risk factors for prostate cancer should not? These are the types of potentially complicated ways to think about supplements in the few areas where strong evidence of benefit exists,” he said.
Interest in neutraceuticals continues to grow, with research suggesting certain phytochemicals such as polyphenols, flavonoids and carotenoids may play a key role in reducing risk for chronic diseases, including cancer, McLymont said. “Some botanicals, however, may pose a health risk because they may cause adverse interactions with a patient’s medical treatment.”
Antioxidants can also present a tricky area for physicians. Many standard chemotherapies work in part by causing oxidative damage. “If a patient is in active treatment and takes antioxidant supplements, will it hinder the treatment effect?” Kushi said. “The jury is still out.”
Patient communication
Regardless of whether or not physicians refer their patients to an oncology nutrition professional, it is critical for physicians to have open, nonjudgmental conversations with their patients about diet, as well as the supplements they are taking, if any. “If you shut down a patient’s explanation of how he’s eating a pound of raspberries a day to receive antioxidant benefits, the patient is not going to be forthright in the future,” Clinton said. “Find out what your patients are doing, and have a rational, scientific-based discussion of the risks and benefits.”
If physicians are unaware of the treatment options their patients are pursuing outside conventional medicine, treatment decisions will be based on false information. “A physician may not know how to explain changes in treatment efficacy or the appearance of adverse effects without full knowledge of any supplements or new diets a patient is using,” Clinton said. “He may look to the treatment itself as a cause of the problem and make adjustments that are not needed and that could be detrimental to the patient.
“In situations where a patient’s clinical course has changed, consider possible food or drug interactions that may be affecting the patient,” he said. — by Tammy Dotts
For more information:
- American Cancer Society. Eat healthy and get active. Available at: www.cancer.org/Healthy/EatHealthyGetActive.
- American Institute for Cancer Research. www.aicr.org/health-professionals.
- American Institute for Cancer Research. www.dietandcancerreport.org. Access date Sept. 28, 2011.
- Basen-Enquist et al. Current Oncology Reports. 2011 Feb. 13(1):71-6.
- Surh YJ. Ann NY Acad Sci. 2011;1229:1-6.
Disclosures: Drs. McLymont and Popplewell and Ms. Meyers reported no relevant financial disclosures.
What role do dietary supplements such as vitamins, herbals, minerals or any combinations of these play in cancer treatment?
There is a wide chasm between thriving and surviving with respect to nutrient intake, especially in the cancer patient.
A healthy human body is self-regulating, self-repairing and heavily dependent on the quality and quantity of nutrients in its diet for health. With those essential axioms, let’s look at the role of nutrition in cancer treatment.
Nutrients can make medical therapy more of a selective toxin to the tumor and less toxic to the patient, hence allowing higher doses and longer cycles of chemotherapy and radiation without patient withdrawal for acute symptoms. Optimal nutrition (food and supplements) can bolster the failing immune system of the cancer patient. Since cancer is an obligate glucose metabolizer, diet and supplements can help to regulate gut and blood glucose to slow cancer growth.
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The simplistic assumption would be that an antioxidant (such as vitamin E or glutathione) combined with a pro-oxidant (such as chemotherapy or radiation therapy) would neutralize each another, leaving the cancer therapy ineffective against the cancer.
But that is not how it works in the human body. Cancer cells are largely anaerobic cells; they do not require nor efficiently absorb antioxidants. As the one exception to this rule, vitamin C is richly absorbed by cancer cells due to the nearly identical molecular structure of ascorbate and glucose, yet the vitamin C in the cancer cells becomes a selective toxin by generating hydrogen peroxide, which is neutralized by healthy host tissues via the enzyme catalase, but this enzyme is absent in cancer cells.
In one study, Lamm and colleagues (Lamm DL. J Urol. 1994; 151:21-26.) provided either low-dose vitamin supplements or high-dose vitamins to bladder cancer patients. The high-dose vitamin group had a 50% reduction in tumor recurrence. In a separate study (Cascinu S. J Clin Oncol. 1995; 13:26-32.), intravenous glutathione reduced neuropathy of cisplatin by 50%. In another study (Jatoi A. J Surg Oncol. 1998; 68:231-236.), modest vitamins given post-surgically to non–small cell lung cancer patients nearly quadrupled lifespan compared to non-vitamin users.
Essentially, many vitamins (ie, vitamin E succinate, or D-3), minerals (ie, selenium), herbs (ie, curcumin), fatty acids (ie, fish oil), food extracts (ie, bovine cartilage), probiotics (bacteria that beneficially colonize the human gut such as Lactobacillus acidophilus) and other non-toxic natural agents are eagerly awaiting their use in comprehensive cancer treatment. The oncologist becomes the hero when incorporating broad spectrum nutrition therapy within the “quiver” of oncology weapons, to augment tumor kill and enhance quality and quantity of life for the patient.
Patrick Quillin, PhD, RD, CNS, is the author of Beating Cancer with Nutrition. Disclosure: Dr. Quillin reported no relevant financial disclosures.
One of the biggest concerns with supplements is potential interaction (positive or negative) with traditional cancer treatments.
The role of dietary supplements in cancer treatment is a major question for patients and practitioners. Ideally, supplements will be able to be used safely and beneficially to enhance the cancer fighting process. The number of supplements and treatment combinations to test for potential interactions is vast.
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The fact that supplements are unregulated is another challenge. With drugs, we don’t proceed from cell line and animal data to clinical practice without human clinical trials. This is not necessarily true of supplements. Unfortunately, the research process takes a long time and patients want supplements now.
Supplements have clearer roles when a deficiency state is present and can be measured — B12, folate and iron, for example — and where dietary sources may be inadequate such as fish oils and vitamin D. When patients are insistent on taking supplements despite the possibility for negative interactions, we can encourage them to consider not taking them the day before, the day of and 2 days after treatment. We may also take into account whether treatment intent is curative or palliative when advising patients.
In the meantime, our patients need to eat. Supplements, as their name suggests, are to add to the diet, not replace it. A well-planned diet is the essential starting point for everyone. Phytochemicals (plant substances) are being discovered that are potent cancer fighters. Might there come a day when doctors prescribe broccoli twice a week or berries daily? Foods are naturally occurring chemical compounds that have impacts similar to pharmaceuticals but to a different degree. Realizing there is little financial gain to food as medicine, researchers and medical economists must find ways to make food research financially viable. This research will likely benefit the fight against other rampant diseases such as obesity, diabetes and heart disease, thereby reducing health care costs in the long term.
Lynne Groeger, MS, RD, CSO, is an oncology dietitian at Peninsula Cancer Institute in Virginia. Disclosure: Ms. Groeger reported no relevant financial disclosures.