The association analysis between fatigue and body composition loss in patients with nasopharyngeal carcinoma during radiotherapy: An observational longitudinal study

Purpose: This study aimed to reveal the association of fatigue with weekly changes in the body composition in patients with nasopharyngeal carcinoma (NPC) and identified the independent strength. Methods: Four body composition indexes and fatigue were assessed before treatment (T0, baseline) and once a week throughout radiotherapy (T1-T7). Generalized additive mixed models (GAMMs) were used to explore the trajectories and longitudinal relationships of fatigue and weekly changes in body composition. The marginal structural model (MSM) was used to control the effect of depression and anxiety. Results: The trajectories of fatigue in 105 participants reached a peak in the fifth week, and changes in body composition started appearing from the second week. Four body composition indexes, weight, body mass index (BMI), body fat rate, and lean body weight loss weekly were positively associated with fatigue. High magnitude of effects was revealed when anxiety and depression were controlled as time-dependent confounders. The positive associations with fatigue were manifested in patients aged >53 years, those with senior high and above education, no drinking, >5000 Y/month of family inflow, >= stage III, or those receiving a dose of >= 70 Gy, >= 3 cycles of induced chemotherapy, and <= 1 cycle of concurrent chemotherapy. Conclusions: Loss of weight, BMI, body fat rate, and lean body weight could be used to independently evaluate the development of fatigue in patients with NPC during radiotherapy. Positive associations between fatigue and weekly body composition loss were found in patients with certain characteristics.