Radiation oncologists at Thomas Jefferson University Hospital are stressing the need for evidence-based, standardized guidelines on dietary recommendations for cancer patients—and with good reason. A new analysis revealed that online dietary recommendations for cancer patients, if even present on an institution's website, appear to be consistently inconsistent.
A review of all 21 of the National Comprehensive Cancer Network (NCCN) member institutions found that only four provided nutritional guidelines, with seven linking to external sites. What's more, many of the sites with recommendations contradicted each other.
The results were published online March 26 in Nutrition and Cancer: An International Journal.
Given that recent data reveals that dietary factors may influence outcomes in patients undergoing cancer treatment, and that over 60 percent of patients head to the Internet for guidance on diet, it's imperative that information is as accurate and uniform as possible, says senior author Colin Champ, M.D., a resident in the Department of Radiation Oncology at Jefferson .
"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. "So we started looking at sources where people may go to see what information they were digesting."
There were discrepancies. Half the information presented or linked to on NCCN sites contradicted the other half.
Half promoted a low-fat, high-carbohydrate diet, and half promoted weight maintenance during treatment, endorsing a 1:1 ratio of carbohydrate to fat. Of the four external sites that provided nutrition guidelines, half favored a low-fat, high-carbohydrate diet, and half favored high-caloric intake to maintain weight.
What's more, the information is not always cancer-site specific, more general recommendations for all cancers are noted. And the weight maintenance recommendations are really less for survivorship and more about not losing weight during treatment, Dr. Champ said.
But depending on cancer type and stage, one might expect different weight changes attributed to these concerns. For instance, recommendations for patients with locally advanced head and neck cancer may diverge dramatically from nutritional recommendations appropriate for patients with localized breast or prostate cancer.
Studies show that the majority of women gain weight during adjuvant treatment for breast cancer, and prospective trials have shown a similar detriment in survival outcomes in obese men during prostate cancer treatment. Promoting low-fat, high-protein diets may cause patients to turn to a high-carbohydrate diet and compound any other weight issues.
It is likely that recommendations favoring calorie-dense diets and therefore weight maintenance are in response to previous findings on weight and cancer. Weight loss during cancer treatment has been associated with a detrimental impact on quality of life, poorer treatment outcomes, and decreased survival time.
Such contradictory information may cause problems for some patients. The lack of data and consistency in recommendations could drastically alter a patient's dietary habits during treatment depending on which site they access.
Many centers, even high-quality institutions such as those reviewed in this study, do not even offer recommendations, and the external referenced websites advocate a variety of nutritional approaches that are inconsistent with each other and NCCN member websites.
"These findings demonstrate an urgent need for consistent, evidence-based nutritional guidelines for patients, and potentially for additional research in this domain," said Dr. Champ.
Explore further: Further research needed to develop evidence-based nutrition guidelines for cancer survivors