Perceived physical fatigability improves after an exercise intervention among breast cancer survivors: A pilot randomized clinical trial.

12050 Background: Among breast cancer populations, exercise interventions resulted in positive but relatively small improvements on fatigue, which may have been masked by using single-item, non-specific measures of global fatigue. Perceived fatigability – whole-body tiredness anchored to standardized tasks/activities of specific intensity and duration – accounts for self-pacing bias as an individual likely titrates their usual activities and exertion level to avoid exhaustion. We examined whether this novel fatigability measure could replace global fatigue in an exercise intervention trial in breast cancer survivors. Methods: This pilot single-center randomized clinical trial of 49 breast cancer survivors was conducted from 2015-17, among which 41 participants (exercise = 22, control = 19) completed the trial and reported their perceived physical fatigability and global fatigue at the first (V1) and the last visit (V3). Perceived physical fatigability was measured using the 10-item, self-administered Pittsburgh Fatigability Scale (PFS) scored 0-50, higher PFS Physical scores = greater fatigability. Global fatigue was assessed with a single question “I have a lack of energy” scored 0 “not at all” to 4 “very much” from the Functional Assessment of Cancer Therapy-Endocrine Subscale (FACT-ES). The exercise intervention consisted of three one-on-one training sessions over 6-14 weeks, plus two optional email/phone consultations. The trainer developed a personalized, home-based exercise program with a goal of achieving the recommended ≥150 minutes/week of moderate to vigorous exercise based on ACSM guidelines. Those randomized to the control group met the trainer for V1 and again 6-14 weeks later at V3, but no exercise prescription was provided. We computed mean differences in perceived physical fatigability and global fatigue between V3 and V1 and compared by intervention groups. Results: Among the 41 women in the study (mean age = 54.9±9.8 years; 80% white), sociodemographic and clinical characteristics were similar by intervention groups, except for antiestrogen use. Post-intervention changes (mean ± SE) in PFS Physical scores were -4.4±1.4 (-22.5%) in the exercise group and 0.2±1.4 (+1.0%) in the control group (p =.022), whereas change in global fatigue scores were -0.64±0.23 in the exercise group and 0.00±0.22 in the control group (p =.054). Conclusions: These findings add to mounting evidence that an exercise intervention reduces fatigue among breast cancer survivors. Importantly, the PFS showed a clinically meaningful reduction after the exercise intervention that was masked when using global fatigue as the measurement. Therefore, the PFS serves as a more sensitive instrument to measure perceived physical fatigability and can better evaluate patient-reported outcomes in future cancer trials, especially those focused on cancer survivorship. Clinical trial information: NCT 02770781.