Long-Term Longitudinal Patterns of Patient-Reported Fatigue After Breast Cancer: A Group-Based Trajectory Analysis

Background: Fatigue is a multidimensional symptom. It is recognised as one of the most burdensome and long-lasting adverse effects of cancer and cancer treatment. We aimed to characterise long-term fatigue trajectories among breast cancer survivors. Methods: We performed a detailed longitudinal analysis of fatigue using a large ongoing national prospective clinical study (CANcer TOxicity, NCT01993498) of patients with stage I–III breast cancer treated from 2012–2015. Fatigue was assessed at diagnosis (baseline), year-one, -two, and -four post-diagnosis. Baseline clinical, socio-demographic, behavioural, tumour- and treatment-related characteristics were available. Trajectories of fatigue and risk factors of trajectory-group membership were identified by iterative estimates of group-based trajectory models and multivariable logistic regression. Findings: Three trajectory-groups were identified for severe global fatigue (N=4173). Twenty-one per cent of patients were in the "High" risk group, having a risk estimate of severe global fatigue of 94·8% [95% confidence interval (CI) 86·6–100·0] at diagnosis and 64·8% [95% CI 59·2–70·1] at year four; 19% of patients clustered in the "Deteriorating" group with a risk estimate of severe global fatigue of 13·8% [95% CI 6·7%–20·9%] at diagnosis and 64·5% [95% CI 57·3–71·8] at year four; and 60% were in the “Low” risk group with a risk estimate of 3·6% [95% CI 2·5–4·7] at diagnosis and 9·6% [95% CI 7·5–11·7] at year four). The distinct dimensions of fatigue clustered in different trajectory groups than those identified by severe global fatigue, being differentially impacted by socio-demographic, clinical, and treatment-related factors. Interpretation: Our findings highlight the multidimensional nature of cancer-related fatigue and the complexity of its risk factors. This study helps to identify patients with increased risk of severe fatigue and to inform personalised interventions to ameliorate this problem. Funding: Susan G. Komen, French Foundation for Cancer Research, Foundation Gustave Roussy, and French Government (Agence Nationale de la recherche [ANR]). Declaration of Interest: None to declare. Ethical Approval: All study participants provided informed consent, and the national regulatory and ethics committee approved the study (ID-RCB:2011-A01095-36,11-039).