What are cancer patients supposed to do with their nutrition when undergoing treatment?

While nutrition may not be the first thing one thinks of when considering cancer treatment, it does play a genuine role as one of the dozens of confounding factors affecting patient outcomes.

And while one would hope that healthcare providers approach this factor with nuance and principled consistency across the board, in reality, how nutrition is handled in the context of cancer treatment involves several guidelines worldwide whose contents aren’t always consistent.

A meta-analysis published in the May 2023 edition of Clinical Nutrition systematically compared and evaluated the quality of nutritional clinical practice guidelines (CPGs) for cancer patients.

This significant analysis is the first to compare existing nutritional CPGs for cancer patients and assess their development quality.

Thus, this meta-analysis ought to be viewed as one of the first significant steps in creating global consistency in healthcare approaches to nutrition in the context of cancer treatment, as doing so will only improve patient outcomes.

Overlap and Differences in Recommendations

The meta-analysis identified several areas of overlap across CPGs, such as nutritional screening and assessment recommendations, which were included in all CPGs except for the JARN (Japanese Association of Rehabilitation Nutrition) set.

Additionally, medical nutrition therapy (MNT) was recommended by the majority of CPGs.

The widely accepted GLIM (Global Leadership Initiative on Malnutrition) criteria for malnutrition diagnosis were suggested as a possible addition to updated versions of the CPGs.

The criteria include a combination of phenotypic (observable physical characteristics) and etiologic (underlying causes) components:

Phenotypic components:

· Unintentional weight loss

· Low body mass index (BMI)

· Reduced muscle mass

Etiologic components:

· Reduced food intake or assimilation

· Disease burden or increased inflammation

A patient must meet at least one phenotypic and one etiologic component to be diagnosed with malnutrition according to the GLIM criteria –which could feasibly occur during chemotherapy which is notorious for its side effect of appetite suppression.

The authors noted that the type of cancer and the stage of its progression plays a significant role in determining the nutritional recommendations a patient may receive.

For instance, some CPGs provided more specific guidance for breast cancer survivors, suggesting a diet rich in vegetables and fruits, along with the explicit recommendation to avoid any supplements that purport to help with recovery.

The highest level of variety among the CPGs was observed in nutrition prescription recommendations.

Nevertheless, a specific point of consistency in this respect was protein intake –which was most often promoted in higher quantities than normal (likely to promote the preservation of muscular tissue that breaks down during intensive cancer treatment.

Another point of consistency in this respect is that most formal guidelines specifically discourage restricted diets during cancer treatment –one is already losing too much weight as it is, so unless one is almost certainly going to die soon, the task for nutritional principles in cancer treatment is to preserve as much of the patient’s appetite as is possible.

Nutritional supplementation recommendations also varied between CPGs, with differences in cannabis preparations, fish oil supplementation, and appetite-enhancing substances.

By that token, one can ascertain that, in most instances, these are superfluities that aren’t likely to hurt but are only ambiguous in their likelihood of helping.

For instance, the DGEM (Deutschen Gesellschaft für Ernährungsmedizin) states that “administration of high doses of antioxidants during chemotherapy is not recommended, and the ESPEN states that vitamins and trace minerals “should be supplied in amounts equal to RDA and discourage the use of high-dose micronutrients in the absence of specific deficiencies.”

By contrast, the AoND (Academy of Nutrition and Dietetics), DAA (Dietitians Association of Australia), ESMO (European Society for Medical Oncology), and countless others lack any formal guidelines on the use of vitamins and trace elements.

Such strange variance is apparent across all factors of nutrition related to cancer treatment and recovery, not just vitamins and trace elements, which means that there is no universal set of formal principles on how to approach nutrition for cancer patients –even in the case of specific types of cancer this is true, not just cancer generally (though that too!)

The level of variance is so large that it is too complex to do justice to in the context of a blog –which shows the extent to which improvements in healthcare guidelines are needed.

Improvements and Future Updates

For instance, many organizations whose guidelines were studied in this meta-analysis lack any recommendations for preventing refeeding syndrome, which is the potentially fatal shift of fluids and electrolytes that can occur in malnourished patients.

As the field of nutrition for cancer patients continues to evolve, it is crucial to update and refine CPGs to provide the most accurate and helpful guidance for clinicians –this means organizations must learn how to corroborate information with each other; otherwise, global inconsistency of treatment and methodology will remain a healthcare norm.

In other words, not all of the organizations whose guidelines were studied account for ways to prevent bad patient outcomes that are known and implemented in other organizations studied.

This is to say, depending on where you live and who your doctor is, how your nutrition is handled as a cancer patient will vary considerably –at times, in magnitudes that could’ve made a positive difference.

It is this which Clinical Nutrition researchers believe needs to change, as such change –in the form of cohesion in treatment principles — will only improve patient outcomes globally.

This meta-analysis is valuable for healthcare professionals and researchers working with cancer patients, highlighting the overlap and differences in recommendations among nutritional CPGs.

By understanding these similarities and differences, clinicians can better tailor their nutritional guidance to individual patients and cancer types.

As the field of nutrition for cancer patients continues to evolve, it is essential to update and refine CPGs to provide the most accurate and helpful guidance for clinicians.