Prevalence, predictors, and characteristics of off-treatment fatigue in breast cancer survivors.

BACKGROUND: Lack of consensus regarding how to identify cancer patients with significant fatigue has hampered research regarding cancer-related fatigue (CRF).
METHODS: Specific criteria were used to identify CRF cases in women with stage 0-II breast cancer (BC group, n = 304). Women completed assessments before adjuvant therapy (baseline), end of adjuvant therapy (Post-Tx), and 6 and 42 months after end of adjuvant therapy (6 and 42 Month Post-Tx). At each, women completed a clinical interview and questionnaires assessing physical and mental health. A healthy control (HC) group with no history of BC (n = 337) completed 2 similar assessments 36 months apart.
RESULTS: Off-treatment CRF prevalence was 9% and 13% at the 6 and 42 Month Post-Tx assessments, respectively. Thus, 15% of the sample evidenced off-treatment CRF with 7% evidencing delayed onset CRF. CRF at the 6 Month Post-Tx assessment was associated only with CRF at baseline (OR = 3.2) and Post-Tx assessments (OR = 3.9). CRF at the 42 Month Post-Tx assessment was associated with CRF at the Post-Tx assessment (OR = 6.1), obesity at baseline, and several baseline measures of coping in response to fatigue. Off-treatment CRF cases differed markedly from CRF noncases and healthy controls on a spectrum of health status indices (mean effect size >1.0 SD).
CONCLUSIONS: Results document the prevalence of off-treatment and delayed onset CRF, suggest the utility of a cognitive-behavioral model of CRF, and support NCCN guidelines recommending monitoring fatigue across the cancer trajectory.