Persistent cancer-related fatigue after breast cancer treatment predicts postural sway and post-exertional changes in sit-to-stand strategy.

Abstract

Chemotherapy-induced peripheral neuropathy (CIPN) is considered a primary mechanism of imbalance among women diagnosed with breast cancer. Recent evidence, however, suggests that cancer-related fatigue (CRF) may also influence balance. Examine the contributions of CRF and CIPN to static and dynamic balance before and after a period of fatiguing exercise. This is a secondary analysis of data examining functional differences between women with breast cancer with and without persistent CRF. Postural sway was measured during static standing and the rising phase of an instrumented sit-to-stand (ISTS) before and after exercise. Regression analyses were performed to determine how CRF and severity of CIPN predicted sway and how much variance was attributable to each. Greater CRF predicted increased pre-, p=.04, and post-exertional, p=.02, static sway in the anterior-posterior plane. CRF accounted for 10.5% and 9.5% of the variance in pre- and post-exertional sway (respectively) compared to the 0.9% and 1.4% accounted for by CIPN severity which was not a significant predictor. After exercise, greater CRF predicted smaller, more conservative, anterior weight shifting during the ISTS, p=.01, and accounted for 6.6% of the variance in sway compared to 3% attributed to CIPN which was not a significant predictor. This analysis is limited by its small and demographically homogenous sample. These results suggest that CRF may influence balance independent of CIPN symptoms. While CIPN remains a risk factor for imbalance in this population, CRF warrants consideration in clinical practice and research as a mechanism of postural instability.