Online Nutritional Advice for Cancer Patients Is Scattershot

Nick Mulcahy

March 29, 2013

Online nutritional advice for cancer patients is inconsistent and contradictory, even that on the Web sites of top cancer centers, according to a new study.

The advice is also sparse, say the researchers, who are from Thomas Jefferson University in Philadelphia, Pennsylvania.

The team reviewed the Web sites of all 21 of the National Comprehensive Cancer Network (NCCN) member institutions and found that only 4 provided nutritional guidelines for patients during treatment. "Very few NCCN institutions provide online specific dietary recommendations for cancer patients," write lead author Colin Champ, MD, and colleagues from the Department of Radiation Oncology at Thomas Jefferson University. Their results appear in the April issue of Nutrition and Cancer: An International Journal.

The Web sites of an additional 5 NCCN centers linked to external sites that provided guidelines. In sum, only 9 of the 21 centers (43%) provided either specific nutritional information or links to sites that do.

Moreover, many of the recommendations posted conflict with each other. "Half of the sites recommend a low-fat diet, while the other half recommend a calorie-dense diet that often advocates the consumption of high-fat foods," the authors report.

This study was inspired by patients. "More and more patients are coming to their doctors and asking for nutritional recommendations before and after treatment, but there is really no standard direction to send them," said Dr. Champ in a press statement.

The authors describe some of the inconsistencies in the online advice. For instance, some of the external Web sites recommend avoiding vegetables and legumes that are calorie-sparse or cause intestinal bloating, including beans, peas, broccoli, cabbage, cauliflower, and Brussels sprouts. This conflicts with recommendations on other external Web sites and several of the NCCN member Web sites.

Different Advice Needed for Different Cancers and Stages

Patients need better resources, note the authors, to learn about "the relative merits of nutritional approaches, not only during treatment, but also during survivorship."

The type and stage of cancer can profoundly influence guidance, they explain.

For instance, nutritional recommendations for patients with locally advanced head and neck cancer who are cachectic can diverge dramatically from recommendations for patients with localized breast or prostate cancer, who can gain weight during treatment.

There are good reasons for the different recommendations, the authors write. Cachectic patients need to maintain weight, whereas other patients might be advised to lose weight.

According to Dr. Champ and colleagues, studies show that the majority of women gain weight during adjuvant treatment for breast cancer, and that weight gain is associated with poorer survival. Prospective trials have shown a similar detriment in survival outcomes in obese men receiving treatment for prostate cancer.

Half of the online sources reviewed in this study recommend diets that minimize fat and protein intake. But this can "lead patients to consume a carbohydrate-heavy diet including simple sugars," the authors note.

In some cancer patients, such a diet is highly problematic. "There is emerging evidence that high blood sugar correlates with disease progression and poorer responses to chemotherapy and disease recurrence," they write.

There are a number of new clinical trials that are designed to restrict caloric intake, especially carbohydrate intake, in cancer patients, including one at Thomas Jefferson University, as reported by Medscape Medical News. The goal is to see if the restriction will improve cancer outcomes.

Among these studies is the first-ever randomized controlled trial to use carbohydrate restriction as a treatment for cancer and to measure a cancer-related outcomes.

The hypothesis that suppressing carbohydrates suppresses or slows cancer growth is supported by a lot of laboratory science, experts say.

"During the past 10 years or so, interest in the metabolism of cancer cells has seen a dramatic increase, which is surely why interest in dietary interventions...has increased," Rainer Klement, MD, a radiation oncologist at the University Hospital of Würzburg in Germany, recently told Medscape Medical News.

In 2011, Dr. Klement and a colleague published a review of the possible role of carbohydrate restriction in both the treatment and prevention of cancer (Nutr Metab. 2011;8:75).

This research was supported in part by the Kimmel Cancer Center NCI-designated cancer center. The authors have disclosed no relevant financial relationships.

Nutr Cancer. 2013;65:430-439. Abstract