Longitudinal assessment of the impact of higher body mass index on cancer-related fatigue in patients with breast cancer receiving chemotherapy.

To assess the impact of obesity on cancer-related fatigue (CRF) in patients with breast cancer, through a secondary analysis of a large, longitudinal, nationwide study of breast cancer patients beginning chemotherapy.

All patients (N = 565; aged 53 ± 10.6) with breast cancer completed the multidimensional fatigue symptom inventory and the symptom inventory to measure CRF symptoms at baseline, post-chemotherapy, and 6 months post-chemotherapy. Height and weight at baseline were used to categorize subjects based on body mass index (BMI): obese (≥ 30.0 kg/m²; n = 294), overweight (25.0-29.9 kg/m²; n = 146), and normal weight (18.5-24.9 kg/m²; n = 125). Multivariate regression models evaluated the relationship of obesity level to CRF over time, controlling for age, menopausal status, race, Karnofsky Performance Status, cancer stage, radiation, and exercise status.

At baseline, the obese had significantly higher CRF symptoms than the normal weight subjects for both the Multidimensional fatigue symptom inventory (MFSI) total (obese = 11.2 vs normal weight = 6.3; p = 0.03) and Symptom Inventory (SI) (obese = 3.5 vs normal weight = 2.9; p = 0.03). Significantly higher SI fatigue scores persisted at post-chemotherapy for the obese (obese = 5.0 vs normal weight = 4.4; p = 0.02). At 6 months post-chemotherapy, the obese patients still had significantly higher SI fatigue scores (obese = 3.5 vs normal weight = 3.0; p = 0.05).Obese patients suffered greater CRF from pre-chemotherapy through 6 months post-chemotherapy. Recommendations for weight loss or weight maintenance may impact CRF levels in obese breast cancer patients before and after chemotherapy.