8:30 am - 9:30 am
A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES PhD Final Exam Seminar by Katherine Ford. This seminar is open to the general public to attend.
Meeting ID: 964 2443 1152
One tap mobile+12042727920,,96424431152# Canada
Thesis Topic: Optimizing Muscle Health in Patients with Colorectal Cancer through Targeted Nutrition Intervention
PhD with Dr. Carla Prado.
Patients with cancer are nutritionally vulnerable and at risk of low muscle mass (MM), a primary nutrition problem that independently predicts poor prognosis. Targeted nutrition interventions to optimize MM should focus on adequate energy and protein intakes. Many patients alter their diet following a diagnosis of cancer but may not consider the corresponding impact on MM. Three studies are presented as part of the Protein Recommendation to Increase Muscle (PRIMe) pilot trial. Patients newly diagnosed with stage II-IV colorectal cancer were randomized to a normal (NP; 1 g/kg body weight [BW]/day) or high protein (HP; 2 g/kg BW/day) diet for 12 weeks and supported with individualized nutrition counselling. One study of baseline data aimed to understand if and why patients made dietary changes post-diagnosis. Patients’ beliefs pertaining to food intake and post-diagnosis dietary changes that had the potential to impact MM were explored using one-on-one semi-structured interviews. A second study included baseline data to characterize total energy expenditure (TEE) and resting energy expenditure (REE) by calorimetry chamber. A third study informed the feasibility of the 12-week intervention: a HP versus a NP diet to halt MM loss (evaluated as appendicular lean soft tissue [ALST] index [ALSTI]) and assessed potential effects on maintaining physical function. The feasibility of sustaining a HP diet and the potential effects of the diets on anthropometrics, body composition, physical activity, energy expenditure, nutritional status, and quality of life were also assessed.
The first baseline study included 29 patients (57±10 years; 62% male; 59% stage III) who reported varied degrees of dietary change that stemmed from internal and external influences. Four main themes emerged to describe dietary decisions after diagnosis: (1) Medical Influences: eating to live; (2) Health Beliefs: connecting lived experiences with new realities; (3) Static Diets: no changes post-diagnosis; and (4) Navigating External Influences: confluence of personal agency and social constraints.
In the second baseline study, 31 patients (56±10 years; body mass index [BMI]: 27.9±5.5 kg/m2; 67.7% male; 74.2% stages II/III colon cancer) were included. TEE (2074±337 kcal/day) did not differ from the lower recommended intake in cancer (25 kcal/kg BW/day) but was below the upper bound of 30 kcal/kg BW/day (-430±322 kcal/d; p<0.001). TEE was variable (21-32 kcal/kg BW/day) and most patients (n=18) had TEE outside of the recommended intake range. REE was higher than predicted by the Mifflin-St. Jeor (145±144 kcal/day; p<0.001) and Harris-Benedict (78±147 kcal/day; p=0.006) equations. ALST, sex, rectal cancer, and presence of an ostomy were among predictors of TEE and REE. In models adjusted for sex, ALST and tumor location independently predicted TEE (both p<0.05).
The third study included 50 patients (57±11 years; BMI: 27.3±5.6 kg/m2; 60% males; 78% colon; 64% stage III). A HP diet was not feasible (mean intake: 1.6±0.5 g/kg BW/day) although individually, 35.3% of patients (n=6) in the HP attained 2.0 g/kg BW/day. This level of protein intake was observed in 8.7% of patients (n=2) in the NP group. Difference between groups trended towards significance for MM (ALSTI HP: 8.2±1.8 kg/m2; NP: 7.2±1.2 kg/m2; p=0.065) but were not observed for physical function. Irrespective of diet allocation, a 1.0 g/kg BW/day increase in protein intake appeared to result in 1.6% increase in ALSTI (β: 1.572; 95% CI: -0.243, 3.387; p=0.090). Positive associations between protein intake and physical function and nutritional status scores were noted.
In conclusion, prior to nutrition intervention, patients altered their dietary choices based on the degree to which food-related decisions provided a sense of control over physical ramifications of cancer. The qualitative approach to this work enabled the opportunity to understand, from the patient perspective, key factors that influence nutritional intake in this population. This thesis also encompassed the largest study to date and the only in the past 25 years to assess TEE of patients with cancer using a calorimetry chamber. Key findings were that energy recommendations, which impact MM, are variable and not an all-encompassing approach to optimize muscle health in patients with cancer. Lastly, this work responded to an international call for research and, to our knowledge, was the first to compare different doses of protein on MM in patients with colorectal cancer. We highlighted the challenge of consuming a HP diet but nonetheless showed the potential for patients to maintain or gain MM through nutrition intervention alone. Overall, this research is a step towards designing definitive trials to assess targeted nutrition interventions to optimize MM in cancer.