Randomized Trial Of Weight Loss On Ghrelin Levels Among Breast Cancer Survivors
This thesis is restricted to Yale network users only. It will be made publicly available on 08/28/2020
Abstract
Purpose: Obesity is associated with increased breast cancer risk and mortality. Ghrelin is a hormone that participates in a negative feedback loop to regulate body weight. Understanding the impact of an individualized, sustainable, dietary and exercise weight-loss intervention on circulating ghrelin levels could provide insight on weight control mechanisms among overweight and obese breast cancer survivors.
Methods: The Lifestyle, Exercise, and Nutrition (LEAN) randomized controlled trial was a 6-month weight loss trial conducted to examine the effect of a weight loss intervention versus usual care on outcomes in 151 breast cancer survivors with BMI ≥ 25 kg/m2. Fasting blood samples were collected at baseline and 6-months and ghrelin was measured using enzyme-linked immunosorbent assays (ELISA). Pearson correlation coefficients were used to examine baseline associations and general linear models and least square means were used to compare changes in ghrelin levels from baseline to 6-months between randomization groups.
Results: Ghrelin measurements from 128 women were analyzed. At baseline, there was a significant positive correlation between circulating ghrelin and age (r=0.28, p<0.001) and significant inverse correlations with weight (r=-0.18, p=0.03), lean body mass (r=-0.18, p=0.02), and leptin (r=-0.18, p=0.03). After adjusting for covariates, among the intervention group, ghrelin levels increased by 12.08% over 6-months versus a 31.05% decrease in the usual care arm (p=0.04). A non-significant greater weight loss was associated with increased ghrelin concentrations among the intervention group (ptrend = 0.67).
Conclusion: These findings support that greater weight loss, achieved through a sustainable diet and exercise intervention, is associated with increased circulating ghrelin levels in overweight or obese breast cancer survivors. Further research is warranted to explore whether this change might affect long-term maintenance of weight loss as well as to further understand the role ghrelin may play in breast cancer recurrence and mortality.