Longitudinal Associations between Inflammatory Markers and Fatigue up to Two Years after Colorectal Cancer Treatment

BACKGROUND: Fatigue is often reported by colorectal cancer survivors and largely impacts their quality of life. Inflammation has been linked to fatigue mainly in patients with breast cancer. Therefore, we investigated how inflammation is longitudinally associated with fatigue in colorectal cancer survivors, up to 2 years posttreatment. METHODS: A total of 257 patients from the ongoing Energy for life after ColoRectal cancer cohort study were included in the analysis. Plasma levels of IL6, IL8, IL10, TNFα, high-sensitivity C-reactive protein (hsCRP), and fatigue were measured at 6 weeks, 6, 12, and 24 months posttreatment. Fatigue was measured through the validated Checklist Individual Strength (CIS; total, 20-140), consisting of four subscales - subjective fatigue (8-56), motivation (4-28), physical activity (3-21), and concentration (5-35), and the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire-Core 30 fatigue subscale (0-100). Linear mixed-models were used to assess the confounder-adjusted longitudinal associations between inflammatory markers and overall fatigue along with the subscales. RESULTS: Mean levels of CIS fatigue decreased from 62.9 at 6 weeks to 53.0 at 24 months. In general, levels of inflammatory markers also decreased over time. No statistically significant longitudinal associations were found between IL6, IL8, IL10, TNFα, and fatigue. Higher levels of hsCRP were associated with more CIS fatigue (β per SD 3.21, 95% confidence interval (CI), 1.42-5.01) and EORTC fatigue (β 2.41, 95% CI, 0.72-4.10). CONCLUSIONS: Increased levels of hsCRP are longitudinally associated with more posttreatment fatigue in colorectal cancer survivors. IMPACT: These findings suggest that low-grade inflammation may play a role in fatigue reported by colorectal cancer survivors up to 2 years posttreatment.