Fatigue in long-term cancer survivors: prevalence, associated factors, and mortality. A prospective population-based study

Background
We compared fatigue severity in breast, prostate or colorectal cancer survivors 5–16 years post-diagnosis with cancer-free controls, and examined factors associated with fatigue and its association with all-cause mortality in survivors.

Methods
Participants of the CAncEr Survivorship - A multi-Regional (CAESAR) study completed the Fatigue Assessment Questionnaire (FAQ) between 2009 and 2011. The FAQ assesses affective, cognitive, and physical fatigue, and sleep problems. We derived the odds of fatigue using logistic regression with the 75th percentile of population norms as the cut-off. All-cause mortality (up to end 2021) was estimated using Cox regression models.

Results
The sample comprised 6057 survivors, of whom approximately one-third reported affective, cognitive, or physical fatigue. Demographic (age, relationship), clinical (chemotherapy), comorbidity (depression), lifestyle, and psychological factors were associated with higher odds of fatigue symptoms and total fatigue. Fatigue symptoms, predominantly physical fatigue, were strongly associated with mortality (unadjusted hazard ratios (HRs) ranged from 1.48 to 2.40). The HRs were attenuated after adjustment for comorbidities and depressive symptoms, although affective and physical fatigue remained independent risk factors for mortality.

Conclusions
Demographic, clinical, comorbidity, lifestyle, and psychological factors were associated with fatigue in long-term survivors. Fatigued survivors have a higher mortality risk. Lowering the burden of fatigue by a comprehensive approach might result in better survival.