Association between fatigue and other cancer-related symptoms in patients with advanced cancer

Although fatigue is the chronic symptom most commonly experienced by patients with advanced cancer, little research has been done on the associations and correlates of fatigue in this population. The aim of this study was, therefore, to determine whether fatigue scores, as measured by the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F), are associated with age, gender, type of cancer diagnosed, pain, and other cancer-related symptoms measured using the Edmonton Symptom Assessment Scale (ESAS).

We retrospectively reviewed the FACIT-F (when a higher score denotes lower fatigue) and ESAS (when a lower fatigue score denotes lower fatigue intensity) scores of 268 patients with advanced cancer who had been previously enrolled in clinical trials of therapies for fatigue. To determine associations between variables, we performed univariate and multivariate analyses on the data.

We found no univariate association between fatigue score and gender, ethnicity (p = 0.31), or type of cancer diagnosed. Performance status was associated with fatigue (p < 0.0001). On multivariate analysis, we found, however, significant association between fatigue and pain (r = -0.20, p = 0.0012), nausea (r = -0.13, p = 0.04), anxiety (r = -0.27, p < 0.0001), fatigue and depression (r = -0.19, p = 0.0019), drowsiness (r = -0.24, p = 0.0002), dyspnea (r = -0.17, p = 0.007), anorexia (r = -0.29, p < 0.0001), insomnia (r = -0.25, p < 0.0001), and feelings of well-being (r = -0.37, p < 0.0001). Using backward stepwise logistic regression analysis, independent correlative factors associated with fatigue include well-being (p = .0003), drowsiness (0.006), anorexia (0.01), and anxiety (0.03). However, this model only explained 21% of the variation in the intensity of fatigue.

Although we found that fatigue is significantly associated with the severity of psychological symptoms (anxiety and depression) and physical symptoms (pain, dyspnea, insomnia, anorexia, and drowsiness), additional research is required to confirm that these are indeed the main associations of fatigue and, by doing so, enable physicians to better characterize fatigue in patients receiving palliative care.