The relationship between interleukin-6, tumor necrosis factor-α, and fatigue in terminally ill cancer patients

Although many cancer patients receiving palliative care experience distressing levels of fatigue, no well-designed studies have investigated contributing factors in Korean patients. We conducted a cross-sectional study using the Brief Fatigue Inventory-K (BFI-K) to measure fatigue while assessing a variety of possible correlates. Ninety patients with incurable cancer in the terminal stage (median survival: 27 days) participated in a structured interview and questionnaire related to their medical conditions and underwent blood sampling for laboratory data and cytokines, including interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha. Body mass index, dyspnea, the Eastern Cooperative Oncology Group performance status, and levels of albumin, blood urea nitrogen (BUN), total bilirubin, and C-reactive protein were significantly associated with fatigue. However, levels of the two proinflammatory cytokines, IL-6 and TNF-alpha, were not significantly correlated with the BFI-K score. In stepwise multiple linear regression, fatigue was related to elevated BUN (beta = 0.376, p = 0.002), severe pain intensity (beta = 0.349, p = 0.004), and impaired performance status (beta = 0.268, p = 0.027), but not related to levels of inflammatory cytokines. In conclusion, the diagnostic work-up and therapeutic plan for patients with cancer-related fatigue should include an evaluation of laboratory parameters, pain severity, and physical performance.