Background: Malnutrition is highly prevalent among adults with cancer and is associated with poorer clinical outcomes, including increased treatment toxicity, complications, prolonged hospitalization, and mortality. Accurate assessment of energy requirements is fundamental to providing individualized nutrition care; however, resting energy expenditure (REE) varies considerably in oncology due to differences in tumor biology, disease stage, systemic inflammation, body composition, and anticancer treatments. Consequently, predictive equations and weight-based recommendations may not adequately reflect individual metabolic needs. This case-based tutorial demonstrates the clinical application of indirect calorimetry (IC) for assessing energy requirements in adult oncology patients.
Methods: Nine adult patients with diverse cancer diagnoses were selected to represent a spectrum of metabolic scenarios encountered in both inpatient and outpatient oncology practice. Each case includes clinical history, nutritional assessment, anthropometric measurements, body composition, handgrip strength, Global Leadership Initiative on Malnutrition (GLIM) classification, dietary intake, and IC-derived REE. Case discussions compare measured REE with guideline-based weight estimates, estimate total energy expenditure (TEE) by incorporating physical activity level, and evaluate overall energy balance.
Results: Considerable variability in measured REE was observed across cases, with both hypermetabolic and hypometabolic states identified. In several patients, IC-derived energy requirements differed substantially from standard weight-based recommendations, highlighting the limitations of generalized predictive approaches. Factors contributing to metabolic variability included systemic inflammation, liver metastases, sarcopenia, recent surgery, and treatment-related effects. Integration of IC findings with comprehensive nutrition assessment provided a more individualized estimation of energy needs and informed tailored nutrition interventions.
Conclusions: These clinical cases highlight the substantial heterogeneity of energy metabolism among adults with cancer and demonstrate the value of IC in refining energy requirement estimates beyond conventional weight-based recommendations. By supporting individualized nutritional assessment and more precise energy prescription, IC has the potential to optimize nutrition care and improve clinical decision-making across a range of oncology settings.