This study measures how much energy cancer patients use when resting, called **Resting Energy Expenditure (REE)**. Using a special method called indirect calorimetry, researchers will see if existing formulas accurately predict these patients' energy needs. They will also explore why some patients burn more or less energy than expected. The study involves one visit for the measurement, and researchers will track your survival over time. Participants must be at least 18 years old, diagnosed with incurable cancer, and able to understand and agree to the study. Those with cognitive issues or who need extra oxygen cannot join.

• **One-time data collection**: Only one visit is needed for measuring REE.
• **No treatment provided**: This study focuses on measuring energy needs, not providing treatment.
• **Eligibility requirements**: Must be a cancer patient without cognitive issues or the need for extra oxygen.