“Tracking cancer-related fatigue during chemotherapy: Insights from a comparative cohort study of early breast cancer patients.” is a publication that investigates the development of cancer-related fatigue (CRF) in breast cancer patients undergoing chemotherapy (CT) and its association with exercise-related variables. The authors aimed to identify distinct fatigue trajectories and understand how physical function correlates with fatigue changes over time.
Study Design and Participants
This cohort study included 100 early breast cancer patients assessed at three timepoints: before chemotherapy (pre-CT), after 8 weeks of CT, and post-CT. CRF was measured using the FACIT-Fatigue scale, and patients were categorized as fatigued (score ≤34) or non-fatigued (>34). Exercise-related assessments included the six-minute walk test (6-MWT) for aerobic capacity, bioelectrical impedance for muscle mass, dynamometry for muscle force, and standardized testing for neuromuscular fatigue. Physical activity was evaluated using the Global Physical Activity Questionnaire (GPAQ).
Key Findings
1. CRF Trajectories
Seven distinct CRF trajectories were identified:
- 34% were never fatigued.
- 25% became fatigued after 8 weeks and remained fatigued post-CT.
- 19% became fatigued only post-CT.
These three patterns accounted for 78% of the cohort, reflecting significant variability in fatigue experiences during treatment.
2. Fatigue Prevalence
CRF prevalence increased from 13% pre-CT to 45% at 8 weeks, reaching 54% post-CT.
3. Exercise Capacity and Physical Function
Fatigued patients had significantly reduced exercise capacity, evident through:
- A 12.1% drop in 6-MWT distance from pre- to post-CT compared to only 0.3% in non-fatigued patients (p < 0.001).
- A decrease of >2.6% in 6-MWT distance between pre-CT and 8 weeks predicted CRF at 8 weeks.
- A >7% decrease in 6-MWT distance from pre- to post-CT predicted CRF post-treatment.
4. Neuromuscular Fatigue
Fatigued patients had significantly higher neuromuscular fatigue in both:
- Knee extensors (p < 0.001)
- Handgrip (p = 0.009)
Interestingly, muscle force and muscle mass did not differ significantly between fatigued and non-fatigued patients, indicating fatigue was more closely linked to neuromuscular endurance than strength.
5. Physical Activity Level
Fatigued patients consistently reported lower physical activity levels across all timepoints (p < 0.001), despite average activity levels remaining stable in the full cohort.
Predictive Modeling
A model combining:
- Knee extensor neuromuscular fatigue,
- 6-MWT distance,
- Knee extensor force,
- Physical activity level
explained 39% of the variance in CRF evolution from pre- to post-CT. This emphasizes the role of exercise-related variables in fatigue development during treatment.
Clinical Implications
The findings highlight the need for:
- Regular CRF assessments during CT,
- Early identification of patients at risk based on declining exercise capacity,
- Initiation of structured exercise programs at CT onset, particularly integrating aerobic and resistance training to address both exercise capacity and neuromuscular fatigue.
Conclusion
This study underscores the importance of tailored interventions for managing CRF in breast cancer patients. CRF during CT is strongly associated with reductions in exercise capacity and increases in neuromuscular fatigue rather than loss of muscle mass or strength alone. Targeting these physical domains through exercise may be key to mitigating CRF and enhancing patient quality of life during and after chemotherapy.Reference: Int. J. Cancer. 2025;1–12. wileyonlinelibrary.com/journal/ijc
