Date of Award

January 2025

Document Type

Thesis

Degree Name

Master of Public Health (MPH)

Department

School of Public Health

First Advisor

Brenda Cartmel

Abstract

Background: Stress, experienced by over one-third of breast cancer survivors, not only leads to significant symptoms and mental health issues, but also increases the risk of breast cancer recurrence and impacts survival. While weight loss lifestyle interventions have been effective in helping breast cancer survivors with obesity lose weight and potentially enhance survival, their impact on stress levels has been inconsistent. The aim of the secondary analysis was to evaluate the effects of a 6-month diet and exercise weight loss intervention on perceived stress in breast cancer survivors.Methods: Breast cancer survivors with a BMI of 25.0 kg/m2 or higher (n=151) who had been randomly assigned to either a 6-month diet- and exercise-weight loss intervention (n=93) or usual care (n=58) in the Lifestyle, Exercise, and Nutrition (LEAN) study were included in the analysis. Perceived stress was assessed using the self-reported Perceived Stress Scale (PSS-10) at baseline and 6 months. Mean baseline to 6-month changes in PSS-10 score were compared by randomization arm using mixed model repeated measures analysis. We also assessed effect modification by baseline PSS-10, marital status, and disease stage and within the intervention group evaluated effects by percent weight loss. Results: At baseline, the average PSS-10 score among the 151 participants was 14.05 (95% CI: 12.92, 15.18). After the 6-month intervention, the intervention group had a significant decrease in stress (PSS-10 -2.52 points (95% CI: -3.78, -1.26)), compared to a decrease of 1.20 points (95% CI: -2.70, 0.30) in the usual care group; but there was not a statistically significant between group difference at 6 months (P = 0.17). Effect modification by baseline stress showed borderline significance (Pinteraction = 0.11). Participants with moderate-to-high baseline stress levels (PSS-10 ≥ 14) in the intervention group experienced a significantly greater reduction in PSS-10 score, -3.00 points (95% CI: -5.44, -0.56) compared to those in the usual care group (P = 0.02), with no between group effect in those with lower baseline stress (0.07 points (95% CI: -2.77, 2.91)). There was no evidence of a dose response effect by percent weight loss in the intervention group. Conclusion: While the LEAN weight loss intervention had no effect on stress levels in overall, our results suggest that the intervention may reduce stress in those women who exhibit initial moderate to high stress levels. Future research should further examine the effect of lifestyle-based weight interventions on stress focusing on women exhibiting higher stress levels.

Comments

This thesis is restricted to Yale network users only. It will be made publicly available on 06/16/2026

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