Higher levels of fatigue are associated with higher CRP levels in disease-free breast cancer survivors

Objective: To investigate the associations between level of fatigue and various potential inflammatory biomarkers for fatigue after multivariate adjustments for possible confounders in a sample of 299 disease-free survivors of breast cancer (BCSs) at a mean of 4 years post diagnosis. Methods: Medical record data were used for cancer-related information, and a follow-up mailed survey collected data on fatigue, depression, anxiety and insomnia symptoms as well as information on demographics, physical health, medication and lifestyle. Blood samples drawn at an outpatient examination were analyzed for leukocyte count, high sensitivity C-reactive Protein (CRP), interleukin 1 receptor antagonist (IL-1ra), interleukin-6 (IL-6), soluble tumor necrosis factor receptor type 1 (sTNF-R1) and neopterin. Results: Fatigue levels were significantly and positively associated with hsCRP (p<.001) and leukocyte count (p=.018), but not with levels of IL-1ra, IL-6, sTNF-R1 or neopterin in unadjusted analyses. Only hsCRP remained significantly associated with fatigue levels in the fully adjusted models (p=.020). Depression and self-rated health also remained independently associated with fatigue: however these variables were not significantly associated with hsCRP in multivariate analyses. Conclusion: In general, and after adjustment for potential confounders, our hypotheses of positive associations between fatigue and several inflammatory markers were not confirmed. However, a small but independent association between level of fatigue and hsCRP was observed and supports the hypothesis that low-grade inflammation could play a role in the pathogenesis of fatigue in BCSs. (C) 2011 Elsevier Inc. All rights reserved.