Laura A. Stokowski, RN, MS
November 20, 2013

Full Story:  http://www.medscape.com/viewarticle/814583

Evidence that diet can prevent cancer or the recurrence of cancer is mounting. In the Women’s Intervention Nutrition Study (WINS), involving breast cancer patients who were on curative therapy, a low-fat diet was associated with reduced risk for cancer recurrence, particularly in those with estrogen-receptor negative cancers.[1] “This is an important study,” comments Suzanne Dixon, “because women with estrogen-receptor negative cancer have fewer treatment options. The low-fat diet had a profound effect on recurrence in this group.”

In the Women’s Healthy Eating and Living (WHEL) study, however, an intense plant-based diet high in fruits and vegetables did not appear to improve survival, but did reduce recurrence when combined with moderate, regular exercise.[2] Still, women with breast cancer often struggle to shed excess weight. “Even if you don’t buy into a dietary effect on survival or recurrence, these are still healthier diets,” remarks Dixon. “Getting cancer isn’t a ‘get out of jail free card’ for heart disease, stroke, hypertension, diabetes and other chronic diseases.”

In The Cancer-Fighting Kitchen,^[3] Rebecca Katz spends little time talking about what foods patients should avoid. “My philosophy is that people hear enough about what they shouldn’t eat. They hear a lot of don’ts. The book is an invitation to shift that thinking.” Katz views the book and its recipes as something that patients and family members can do to combat cancer, at a time when helplessness is a common feeling.

Along with maintaining a healthy attitude, avoiding illness and infection, and exercising regularly, research shows that what cancer patients eat can influence cancer progression, recurrence risk, and survival.^[4] Foods have many cancer-fighting properties, including anti-inflammatory, antimicrobial, and proimmune system effects. The right foods can stimulate appetite, aid in digestion, and relieve gastrointestinal side effects, all of which are important in preventing involuntary weight loss.

Food is a key part of a risk-reduction strategy for cancer, says Katz. In The Cancer-Fighting Kitchen, she provides an important tool for incorporating cancer-fighting foods into the diet. The chapter “The Culinary Pharmacy” is an A-to-Z resource detailing the evidence-based cancer-fighting properties of foods, herbs, and spices. These compounds are the foundation of the book’s recipes, which, by combining many of the cancer-fighting foods, increase the chances of yielding benefit.

Katz emphasizes whole foods in her recipes for cancer patients. “Whole foods provide the most nutrient density,” explains Katz. “When patients are going through cancer, every bite counts. From day to day, they don’t know how much they will be able to eat. Whole/organic foods provide the most bang for their buck. Furthermore, organic foods usually contain fewer toxins, so for the patient who is exposed to the toxic effects of chemotherapy, organic foods don’t add to this burden.” Although organic might be optimal, eating conventional produce is preferable to eating no produce at all. This important message should be conveyed to patients who may not have access to organic foods, or who may not be able to afford them.

“Extreme” Dietary Manipulations

In recent years, interest in dietary manipulations in the treatment of cancer has increased, but the optimal strategies are not known. In preclinical studies, metabolic dietary therapies, such as calorie restriction, fasting, and ketogenic diets, have been shown to slow the growth of cancer, but few human clinical trials have been conducted.^[5] Calorie restriction has been shown in murine models of breast cancer to repress tumor growth in an additive manner during radiation therapy.^[6]

The ketogenic diet, which is very high in fat, involves eliminating nearly all carbohydrates from the diet, because cancer cells consume glucose derived from carbohydrates. Used for many decades to treat pediatric epilepsy, this very-low-carbohydrate diet strategy is aimed at starving cancer cells that are dependent on glucose, which has both direct and indirect effects on tumor proliferation.^[7]

Dixon comments that experimental aggressive diet interventions, such as the ketogenic diet, are not yet officially recommended in cancer guidelines. “Tumor biology is very complicated. What works for one tumor type is not necessarily going to be helpful for another. Moreover, the ketogenic diet is quite extreme. We need to make sure that patients will benefit, and not be harmed by it, before we recommend this diet.”

Another intervention, which has shown promise in murine studies, is fasting before undergoing chemotherapy.^[8] Explains Dixon, “This involves the patient fasting for a day or two before chemotherapy, on the day of chemotherapy, and for a day or two afterwards. Fasting generally means drinking only water; no calories are ingested. The theory is that cancer is caused by uncontrolled growth and replication, so that by fasting and putting the body into a calorie-deficit state, the healthy cells become quiescent and go into ‘housekeeping mode.’ Only basic functions are carried out, but no growth or replication. This protects the healthy cells from the effects of chemotherapy, so patients will experience fewer or reduced side effects. The effect on the cancer cells is to sensitize them to chemotherapy, so that they are more susceptible to it.”

However, Dixon emphasizes that “this is not yet a proven strategy, and it has mostly been patient-driven. It may be effective only for certain tumors; we don’t know yet. But patients are reading about it online and want to try it. It’s not being officially recommended, but some patients are doing it.”

Does fasting work? Anecdotally, patients are reporting fewer side effects, such as mouth sores, diarrhea, and skin issues, says Dixon. An obvious question, however, is whether fasting is safe in patients who are at high risk for weight loss and cachexia. “We need to figure out how to do it safely,” agrees Dixon. “In tumor types where it is unlikely that the patient will lose a lot of weight, we wouldn’t be as concerned about short-term fasting. Most patients with such cancers as breast and prostate aren’t losing a lot of weight doing it. And even if fasting does turn out to be safe, it will be important for patients to load up on fluids and keep the kidneys functioning. We need clinical trials — in the next few years, we will have more data to sort out who will benefit and who shouldn’t do it.”

Nutrition Near the End of Life

What and how much to feed a patient nearing the end of life can be a dilemma, especially for family members. “People equate food with love,” explains Dixon, “and sometimes push food too hard, especially if the patient has an enteral feeding tube. They want to keep feeding the dying patient. We need to educate caregivers and family members that a normal part of the dying process is for organs to shut down. Pushing fluids at that time can do more harm than good.” Dixon emphasizes that it’s very important to work with the hospice team to pick up clues about when nutrition should be dialed back; these may pertain to decreased activity, or signs of fluid overload. “Families need to know that the patient is not hungry near the end of life,” says Dixon.

If the patient still has months to live, even if cachexic, continuing nutrition will help with strength and quality of life. “If early satiety is a problem, administer enteral feedings through the feeding tube at night, give them more slowly, and keep the head of the bed elevated to avoid reflux. Try to get some nourishment in without making the patient uncomfortably full.” Generally, Dixon advocates that patients in palliative care should be kept as well-nourished as possible so they don’t die of malnutrition before they would die of their tumor. When a patient reaches days to weeks to live, however, nutrition usually isn’t helpful.

Rebecca Katz, who has experience working as a cook for patients with cancer, shares what she has learned about food at the end of life. “I once worked with a family whose dying mother requested French toast — really good French toast. Her family went bananas and said, ‘No, no — it’s not healthy, you can’t have that.’ So I made her a little piece of French toast so that she could just put it in her mouth to taste it. People have to remember that food is an emotional issue until the very end. Sometimes people just want to taste something wonderful — maybe without even swallowing it. Taste buds, even when dulled, have a memory.”

Food for Thought — and Health

The success of cancer treatment depends on the patient’s ability to tolerate it, which in turn depends on the patient’s nutritional status before treatment begins. Nutritional screening is therefore critical to outcomes.

The role of nutrition throughout cancer treatment is also important, and often underestimated. Good nutrition can mitigate the side effects of treatment, improve quality of life, and raise the chances of survival. The nutritional issues that may be encountered in patients with cancer are vast, so early referral to a specialist in oncology nutrition provides the best chance of success. Consistent, evidence-based guidelines for nutrition in patients with cancer are urgently needed.^[9]

By providing the right tools to patients, they can experience feelings of empowerment as they take control of their nutritional health, which can only be advantageous to their treatment outcomes and quality of life.

References

1. Chlebowski RT, Blackburn GL, Thomson CA, Nixon DW, Shapiro A, Hoy MK. Dietary fat reduction and breast cancer outcome: interim efficacy results from the Women’s Intervention Nutrition Study. J Natl Cancer Inst. 2006;98:1767-1776. Abstract
2. Pierce JP, Natarajan L, Caan BJ, Parker BA, Greenberg ER. Influence of a diet very high in vegetables, fruit, and fiber and low in fat on prognosis following treatment for breast cancer: the Women’s Healthy Eating and Living (WHEL) randomized trial. JAMA. 2007;298:289-298. Abstract
3. Katz R. The Cancer-Fighting Kitchen. Berkeley, Calif: Celestial Arts; 2009.
4. Rock CL, Doyle C, Demark-Wahnefried W, et al. Nutrition and physical activity guidelines for cancer survivors. CA Cancer J Clin. 2012;62:243-274. Abstract
5. Simone BA, Champ CE, Rosenberg AL, et al. Selectively starving cancer cells through dietary manipulation: methods and clinical implications. Future Oncol. 2013;9:959-976. Abstract
6. Klement RJ, Kämmerer U. Is there a role for carbohydrate restriction in the treatment and prevention of cancer? Nutr Metab (Lond). 2011;8:75.
7. Saleh AD, Simone BA, Palazzo J, et al. Caloric restriction augments radiation efficacy in breast cancer. Cell Cycle. 2013;12:1955-1963. Abstract
8. Lee C, Raffaghello L, Brandhorst S, et al. Fasting cycles retard growth of tumors and sensitize a range of cancer cell types to chemotherapy. Sci Transl Med. 2012;4:124ra27.
9. Champ CE, Mishra MV, Showalter TN, Ohri N, Dicker AP, Simone NL. Dietary recommendations during and after cancer treatment: consistently inconsistent? Nutr Cancer. 2013;65:430-439.