Cancer-related fatigue: the impact of skeletal muscle mass and strength in patients with advanced cancer

BACKGROUND: Although exertional fatigue is directly and negatively related to skeletal muscle mass and strength, it is currently unknown if these variables are associated with cancer-related fatigue (CRF). Therefore, the purpose of this study was to determine if CRF is associated with measures of appendicular lean muscle mass and strength in advanced cancer patients (ACP). METHODS AND RESULTS: Eighty-four patients (48 men, 36 women aged 61.6 ± 13.2 year) newly diagnosed (≤6 months) with inoperable (Stages III-IV) gastrointestinal or non-small cell lung cancer participated in this study. All patients completed the Brief Fatigue Inventory (BFI). Handgrip (HGS) and quadriceps (QS) strength were assessed using isometric and isokinetic dynamometry, respectively. Skeletal muscle mass index (SMMI) was calculated from the appendicular lean mass measured via dual-energy X-ray absorptiometry divided by body height squared. Univariate analysis showed BFI to be significantly associated with body mass index, weight loss, anemia, hypoalbuminemia, activity level, pain, depression, and sarcopenia along with SMMI, HGS, and QS. HGS (r = -0.34; p = 0.018), QS (r = -0.39; p = 0.024), and SMMI (r = -0.60; p < 0.001) were negatively correlated with BFI total scores in men but not in women. When adjusted for sex, age, diagnosis, survival, along with the above characteristics, multivariate analyses showed that BFI scores were negatively associated with HGS (B = -0.90; 95% CI -1.5:-0.3), QS (-0.2; -0.3:-0.01), and SMMI (-7.5; -13.0:-2.0). There was a significant sex × SMMI interaction (10.8; 1.2:20.5), where BFI decreased with increasing SMMI in men, but did not change with SMMI in women. CONCLUSION: These results suggest that in ACP, CRF is related to muscle mass and strength, which may provide targets for future interventions.