Defining Cachexia in Children With Cancer in the United States: Developing a Framework to Inform Clinical and Research Practice.

BACKGROUND: Cancer cachexia describes the muscle and weight loss, anorexia, and physical impairment common in certain adult cancers. No formal criteria exist to define paediatric cancer cachexia, making its clinical recognition and impact largely unknown. Using established undernutrition guidelines, criteria were developed to identify potential cachexia in children with cancer based on standardised anthropometric measures or diagnostic codes. METHODS: The Surveillance, Epidemiology, and End Results and Optum Electronic Health Records databases were used to estimate prevalence and incidence rates of cancer and cancer cachexia between 2017 and 2021 in patients aged < 20 and < 18 years, respectively. In the absence of a consensus definition for paediatric cachexia, four sets of candidate criteria were developed based on body weight for length/height or body mass index z-scores, or reduced gain or loss of body weight, corresponding to mild or severe undernutrition. A fifth criterion required a potentially cachexia-related ICD-10-CM diagnosis code. RESULTS: This study included 26,855 paediatric patients (aged < 18 years) with cancer; ~90% were aged ≥ 2 years. Epidemiologic estimates for cancer cachexia prevalence and incidence rate varied considerably by age, cancer type and cachexia definition. Estimates were low for most categories, especially in the youngest age groups; however, cachexia was difficult to assess in patients aged < 2 years due to small patient numbers. CONCLUSIONS: We describe one of the first attempts to develop potential paediatric cachexia criteria. These criteria and resulting data provide a framework to inform further research into generating consensus guidelines for the identification of childhood cancer cachexia.