This is an observational study to assess the determinants of energy expenditure in cancer, and how those change throughout the disease trajectory. The investigators hypothesize that skeletal muscle will be the primary determinant of energy expenditure throughout the disease trajectory.

Proper nutrition is a hallmark of successful cancer treatment. Adequate energy intake helps to maintain body weight and composition, improving outcomes such as response to therapy, quality of life, and survival. Unfortunately, little is known about energy needs in cancer, as few studies have assessed energy expenditure (the amount of calories used/day). Furthermore, individuals with cancer often experience muscle loss (sarcopenia), changes in physical activity, and undergo treatment, all of which might substantially alter energy needs. Equations to estimate energy REE (and thus dietary requirements) were created from cohorts of healthy individuals, and no tools that can be easily used in clinical settings are validated to assess REE.

The overarching aim of this study is to evaluate the largest component of energy needs - resting energy expenditure (REE) in relation to body composition (skeletal muscle, adipose tissue) and physical activity in a cohort of patients with colorectal cancer. Other aims will explore the changes in energy expenditure and determine the accuracy of a portable indirect calorimeter for measuring REE.

Newly-diagnosed individuals with stage II-IV colorectal cancer will undergo indirect calorimetry to assess REE. Body composition will be measured by CT scans, with sarcopenia status based on previously published cut-points. Nutritional status and inflammation (C-reactive protein, neutrophil:lymphocyte) will be assessed as confounding variables.

Total energy expenditure will be measured near treatment start in a sub-sample of 20 participants with colorectal cancer using doubly labeled water and accelerometers. Participants will wear accelerometers (ActiCal) for 14 days to provide detailed physical activity data.These assessments will also be preformed in a sub-sample of 20 participants after treatment end.

An additional part of this study will assess the validity of a portable indirect calorimeter for measuring REE. To address this, a sub-group of patients will be invited to undergo an additional test of REE using a portable indirect calorimeter, the FitMate (COSMED). Results will be compared using Pearson's correlation, dependent samples t-test, and Bland-Altman analysis to assess agreement between the FitMate and validated indirect calorimeters (VMax metabolic cart and whole body calorimtery unit). Exploratory outcomes include phase angle by bioelectrical impedance analysis, handgrip strength, calf circumference, and nutrition status by patient generated subjective global assessment (PG-SGA).

The results from this project will provide a basis of better energy recommendations to sustain body weight and composition, thereby improving prognosis in cancer.

Pre-treatment Participants:

Inclusion Criteria:

• Recent diagnosis of colorectal cancer (stage II-IV);
• Able to arrive at the Human Nutrition Research Unit fasted;
• Patients undergoing treatment should be able to undergo measurements within 20 days of treatment commencement;
• Able to provide written informed consent;
• Able to communicate freely in English;
• Age 18-90

Exclusion Criteria:

• Recent (within the past month) anti-cancer therapy;
• Recent invasive surgery (within the last 4 weeks);
• Women during pregnancy or are breast-feeding;
• Inability to breathe under the indirect calorimeter hood for 20-30 minutes;
• Severe toxicity during the 1st cycle therapy (where applicable);
• Severe mobility issues (e.g. confined to wheelchair);
• Use of medications that may affect body composition or metabolism will be evaluated individually (e.g. cortico-steroids, hormone replacement, etc.)
• Patients with a pacemaker

Post-treatment participants:

Inclusion Criteria

• Recently (<3 year) completed adjuvant chemotherapy treatment for colorectal cancer (stage II-IV)
• Able to arrive at the Human Nutrition Research Unit fasted
• Able to provide written informed consent
• Able to communicate freely in English
• Age 18-90

Exclusion Criteria

• Recent (within the past month) anti-cancer therapy
• Recent invasive surgery (within the last 4 weeks)
• Women during pregnancy or are breast-feeding
• Inability to breathe under the indirect calorimeter hood for 20-30 minutes
• Severe mobility issues (e.g. confined to wheelchair)
• Use of medications that may affect body composition or metabolism will be evaluated individually (e.g. cortico-steroids, hormone replacement, etc.)
• Patients with a pacemaker

Patients with colorectal cancer (stage II-IV) at the Cross Cancer Institute (Edmonton, Alberta, Canada)