Determinants of long-term fatigue in breast cancer survivors: results of a prospective patient cohort study

OBJECTIVE: Fatigue is among the most distressing symptoms across the breast cancer continuum. However, little is known about the factors contributing to long-term persisting fatigue. Therefore, we explored determinants of long-term physical, affective, and cognitive fatigue in a prospective cohort of breast cancer patients.

METHODS: Breast cancer patients recruited in a population-based case-control study (MARIE study) provided comprehensive data on sociodemographics, lifestyle, and preexisting medical conditions. At follow-up (median 6.3 years post-diagnosis, MARIEplus), disease-free cancer survivors (N = 1928) reported current fatigue using a validated multidimensional questionnaire. Additionally, survivors retrospectively rated their fatigue levels before diagnosis, during the treatment phase, and 1 year post-surgery. Linear regression analyses were performed.

RESULTS: As major determinants of long-term physical, affective, and cognitive fatigue, multiple regression analyses revealed preexisting psychological or depressive disorders, migraine, analgesic use, peripheral arterial obstructive disease (PAOD), and arthritis. A physically inactive lifestyle and obesity were associated with persisting physical fatigue. Aromatase inhibitors were also associated with long-term fatigue, especially cognitive fatigue. Chemotherapy and, to a lower extent, radiotherapy were major contributors to the development of fatigue during the treatment phase, yet were not associated with long-term fatigue.

CONCLUSIONS: Although the development of fatigue in breast cancer patients seems largely impacted by cancer therapy, for the long-term persistence of fatigue, preexisting medical or psychological conditions related to depression or pain and lifestyle factors appear to be more relevant. Physicians, psycho-oncologists, and researchers may need to distinguish between acute fatigue during therapy and long-term persisting fatigue with regard to its pathophysiology and treatment.