Fatigue is very common among colorectal cancer (CRC) patients. We examined the association between adherence to the World Cancer Research Fund/American Institute for Cancer Research (WCRF/AICR) lifestyle recommendations and fatigue among stage I-III CRC patients, and whether inflammation mediated this association. Data from two prospective cohort studies were used. Adherence to the WCRF/AICR recommendations was expressed as a score ranging from 0-7, and assessed shortly after diagnosis. Six months post-diagnosis, fatigue was assessed with the European Organization for Research and Treatment of Cancer quality of life questionnaire C30 (EORTC QLQ-C30), and in a subpopulation, the plasma levels of inflammation markers (IL6, IL8, TNFα, and hsCRP) were assessed. Multiple linear regression analyses were performed to investigate the association between adherence to the WCRF/AICR recommendations and fatigue. To test mediation by inflammation, the PROCESS analytic tool developed by Hayes was used. A higher WCRF/AICR adherence score was associated with less fatigue six months after diagnosis (n = 1417, β -2.22, 95%CI -3.65; -0.78). In the population of analysis for the mediation analyses (n = 551), the total association between lifestyle and fatigue was (β -2.17, 95% CI -4.60; 0.25). A statistically significant indirect association via inflammation was observed (β -0.97, 95% CI -1.92; -0.21), explaining 45% of the total association between lifestyle and fatigue (-0.97/-2.17 × 100). Thus, inflammation is probably one of the underlying mechanisms linking lifestyle to fatigue.
Keywords: colorectal cancer; fatigue; inflammation markers; lifestyle; mediation analyses.