Post-cancer fatigue is not associated with altered cytokine production

Background: Prolonged fatigue after cancer treatment is common. The pathophysiology of such post-cancer fatigue (PCF) is unknown, although cross-sectional studies suggest increased pro-inflammatory cytokine production. This study investigated the association between cytokine levels and fatigue from the time of treatment to 12 months later. Patients and methods: A representative nested case-control series was derived from a prospective cohort of women treated for early-stage breast cancer, including 13 PCF cases and 15 matched control subjects who recovered uneventfully. Serum levels and in vitro production of the cytokines interleukin (IL)-1α, IL-2, interferon (IFN)-γ, IL-4, IL-6, IL-10, IL-12, and tumour necrosis factor (TNF)-β were measured by multiplex immunoassay in longitudinally collected samples. In addition, serum levels of neopterin and the anti-inflammatory regulators, IL-1 receptor antagonist, sIL-6R, and sTNF-rII, were assayed by enzyme-linked immunosorbent assay. Flow cytometric analysis of activated leukocyte subsets was performed. Results: No significant differences in any of these parameters were found between cases and control subjects. Cytokine levels and symptoms showed no clear correlation pattern. Conclusion: The findings in this well-characterised subject group argue against the notion that PCF is mediated by peripheral inflammation.