Pro-inflammatory cytokine levels and cancer-related fatigue in breast cancer survivors: Effects of an exercise adherence program

Purpose: This study aimed to determine the effect of an exercise intervention on subjective cancer-related fatigue (CRF) and pro-inflammatory cytokine levels in breast cancer survivors (BCS). Methods: BCS with greater than moderate CRF (≥ 4) were recruited and randomly assigned to experimental or control groups. The experimental group participated in a 12-week exercise adherence program (Better Life after Cancer - Energy, Strength, and Support; BLESS). Interleukin (IL)-6 and tumor necrosis factor-α (TNF-α) levels were determined at 3 time points (M1: Baseline, M2: Post-intervention, and M4: 6 months after intervention). Subjective fatigue was measured using the Korean version of the revised Piper Fatigue Scale. Results: In this analysis of participants with physiological fatigue measures available (19 experimental, 21 control), there were no statistically significant differences in IL-6 (F = 1.157, p = 0.341), TNF-α levels (F = 0.878, p = 0.436), and level of fatigue (F = 2.067, p = 0.118) between the 2 groups at baseline. Fatigue in the experimental group showed statistically significant improvement compared to the control only at M2 (p = 0.022). There was no significant relationship between subjective and physiological fatigue at the 3 measurement points. Conclusion: The BLESS intervention improved CRF in BCS immediately at post-intervention, and this study presents clinical feasibility for the management of CRF in BCS in the early survivorship phase who are already experiencing fatigue.