Preoperative Definition of Malnutrition Varies by Cancer Type

Fran Lowry

March 05, 2020

Many cancer patients are malnourished as they go into surgery, and that raises their risk for complications.

Dr Nicholas McKenna

"Cancer patients have an estimated prevalence of malnutrition ranging from 20% to 70%," Nicholas P. McKenna, MD, from the Department of Surgery at the Mayo Clinic, Rochester, Minnesota, told Medscape Medical News.

"We know that malnutrition raises the risk of complications from a major cancer operation," he continued. "But patients can improve their nutritional status through preoperative rehabilitation, or prehabilitation programs that offer nutrition counseling, nutritional supplementation, and exercise."

These prehabilitation programs need to be adopted to the patient. This starts with assessing for malnourishment, which in turn is related to which type of cancer the patient has.

McKenna was the lead author of a new study that found that in the assessment of preoperative risk, common definitions of malnutrition do not apply to all cancers. His team developed new definitions for different types of cancer.

"Our hope is that clinicians will use these definitions of malnutrition to better identify patients who will benefit from prehabilitation," he said.

The study was published online February 26 in the Journal of the American College of Surgeons.

Currently, common definitions of malnutrition rely on unintentional weight loss and/or body mass index (BMI), McKenna explained.

However, different definitions of malnutrition are used in risk assessment, and until now, there has been no evidence as to which is best, he said.

"So, we decided to determine which definition was best to use in the preoperative setting to assess risk. And as we got deeper into it, we began to realize that not all cancers were the same, so we decided to see whether different definitions of malnutrition were more or less applicable, depending on the cancer type," McKenna said.

With that aim, the researchers analyzed clinical registry data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database.

They identified 205,840 operations performed from 2005 to 2017 for six types of cancer: colorectal (74%), esophageal (3%), gastric (3%), hepatic (2%), pulmonary (9%), and pancreatic (10%).

Using multivariable logistic regression, the researchers evaluated the effect of malnutrition on the risk for any major postoperative complication (represented as a composite that included infections, pulmonary problems, stroke, and heart attack) or death within 30 days of the surgery.

Nutritional status was evaluated using European Society for Parenteral and Enteral Nutrition (ESPEN) criteria for malnutrition; the ACS NSQIP risk factor of unintentional weight loss of >10% over the prior 6 months; and the World Health Organization (WHO) BMI classification system.

"ESPEN defines malnutrition in two ways, by age and by BMI," McKenna said.

"The first is by age, so for patients younger than 70 years, it would be a BMI below 20 kg/m2. And for patients 70 and older, it is a BMI below 22 kg/m2, plus unintended weight loss >10% body weight over any time, or more than 5% in the past 3 months. We call this ESPEN 1," he explained.

"The second way is having a BMI below 18.5 alone, which the WHO considers severely thin. We call this ESPEN 2," he said.

McKenna and his team added their own definitions of severe malnutrition and mild malnutrition. Severe malnutrition was defined as the combination of a BMI <18.5 kg/m2 and weight loss of >10%. For mild malnutrition, it was a BMI of 18.5 to 20 for patients younger than 70 or a BMI <22 for patients aged 70 or older.

They called the final malnutrition definition "NSQIP." The criteria for this definition was weight loss >10% with a normal BMI (>20 kg/m2 for patients younger than 70 and >22 kg/m2 for patients aged 70 or older).

The researchers then evaluated the risk for major postoperative complications associated with each nutritional category, including obesity and the absence of malnutrition, for all patients and by cancer type.

"We found that using a one-size-fits-all approach across all cancer types when counseling a cancer patient preoperatively could result in overestimating or underestimating the patient's risk of complications after a major cancer resection procedure," McKenna said.

The definition that best predicted postoperative risk differed for the six cancer types were as follows:

  • Colorectal: severe malnutrition

  • Esophageal: ESPEN 2

  • Gastric: ESPEN 1

  • Hepatic: NSQIP

  • Pulmonary: ESPEN 1

  • Pancreatic: ESPEN 1

"A definition of malnutrition was bad for the most part, but severe malnutrition, which is a low BMI and unintended weight loss, was the worst in terms of outcomes, but only for colorectal and esophageal cancer," McKenna said.

ESPEN 1 was the strongest predictor of mortality and major morbidity for patients with gastric cancer and lung cancer, and NSQIP was the strongest predictor of mortality for patients with liver cancer.

Definitions Should Guide Prehabilitation

"With the increasing use of prehabilitation programs, we think our results will help clinicians target the right patients," McKenna said.

"For example, for gastric cancer and for liver cancer, being severely malnourished had a neutral effect on their morbidity and mortality. The patients who meet these criteria that do make it to surgery probably aren't at the same risk as someone that has ESPEN 1. The information can help guide you to look at the different definitions of malnutrition and then inform you which definition you might want to use for a specific cancer type," he said.

The study was funded by the Mayo Clinic. McKenna reports no relevant financial relationships.

J Am Coll Surg. Published online February 26, 2020. Abstract

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