Inflammation and dimensions of fatigue in women with early stage breast cancer: A longitudinal examination.

Abstract

Fatigue is a common and long-lasting side effect of cancer. Although fatigue is a multidimensional symptom, biologic mechanisms of fatigue dimensions have not been identified. Women recently diagnosed with early stage breast cancer (n = 192) completed assessments before and after adjuvant therapy and at 6-month, 12-month, and 18-month posttreatment follow-up visits. At each assessment, women completed the Multidimensional Fatigue Symptom Inventory and provided blood for protein markers of inflammation (tumor necrosis factor [TNF] alpha [TNF-α], soluble tumor necrosis factor receptor type II [sTNF-RII], interleukin 6 [IL-6], and C-reactive protein [CRP]). Mixed-effect linear models examined within-person and between-person associations between inflammatory markers and dimensions of fatigue. Analyses demonstrated a positive within-person association between general fatigue and TNF-α (b = 1.67; p = .037), sTNF-RII (b = 2.77; p = .002), and IL-6 (b = 0.86; p = .010) when controlling for age, race, education, body mass index, and cancer stage. Similarly, there was a positive within-person association between physical fatigue and TNF-α (b = 1.58; p = .007), sTNF-RII (b = 2.38; p < .001), and CRP (b = 0.43; p = .007). Conversely, there were negative within-person associations between emotional fatigue and TNF-α (b = -1.92; p = .004) and sTNF-RII (b = -2.10; p = .006). General and physical fatigue were positively associated with CRP at the between-person level (b = 0.82, p = .024 for general; b = 0.71; p = .012 for physical). No significant associations between mental fatigue and inflammatory makers were found. The current findings identified distinct dimensions of fatigue associated with inflammatory activity in women with breast cancer and highlighted individual variability in inflammatory markers as a key predictor of fatigue symptoms.