Protein Recommendation to Increase Muscle (PRIMe): Study protocol for a randomized controlled pilot trial investigating the feasibility of a high protein diet to halt loss of muscle mass in patients with colorectal cancer.

Background: Severe muscle mass (MM) loss is a defining feature of cancer observed across all types and stages of disease and is an independent predictor of poor clinical outcomes including higher incidences of chemotherapy toxicity and decreased survival. Protein is essential to build MM, yet the optimal amount for preventing or treating muscle loss in patients with cancer remains undefined.

Methods: The Protein Recommendation to Increase Muscle (PRIMe) study is a single-center, two-armed, parallel, randomized, controlled pilot trial that assesses the feasibility of utilizing a high protein (HP) diet to positively impact clinical outcomes in people undergoing chemotherapy to treat colorectal cancer. Forty patients with newly diagnosed stage II-IV colorectal cancer who are scheduled to receive chemotherapy will be included. Participants are randomly assigned to a HP or normal protein (NP) diet for twelve weeks. The HP and NP groups receive nutrition recommendations to achieve 2.0 g of protein per kilogram of body weight per day (g∙kg∙d) and 1.0 g⋅kg⋅d, respectively. These values refer to the upper and lower recommended range of protein intake for people with cancer. Energy recommendations are based on measured energy expenditure. Assessments are completed within two weeks of starting chemotherapy (baseline), at week 6, and at week 12. Changes to skeletal MM, physical function, anthropometrics, body composition, muscle strength, physical activity, energy metabolism, metabolic markers, nutritional status, quality of life, readiness to change and psychosocial determinants of behavioural change are assessed between the HP and NP groups. Feasibility of the nutritional intervention is assessed by change in MM as a surrogate marker.

Conclusions: This evidence-based study investigates the feasibility of increasing protein intake following a diagnosis of cancer on clinical outcomes during treatment for colorectal cancer. This study will inform larger trials assessing the impact of increasing protein intake in cancer to determine their importance and integration into standard clinical care for people with cancer.