Predictores e impacto de la fatiga sobre el estado de salud de las largas supervivientes de cáncer de mama

Résumé

More effective cancer therapies and early detection have led to an increased number of those women transitioning from breast cancer patient to survivor. However, breast cancer survivorship has become a phase of continuous care of the cancer patient due to the chronicity of the sequels that they still suffer. Specifically, during the long-term breast cancer survivorship stage (≥ 5 years since cancer diagnosis), they must deal with a whole array of sequels related to the disease itself and/or the treatments received, which are present many years after the completion of the treatment or even for life. Among these ongoing sequels, one of the most common and disabling is cancer-related fatigue and its persistence. Thus, in order to continue developing effective treatment strategies that address this symptom many years beyond breast cancer diagnosis and the end of oncology treatment received, it was necessary to further deepen and carry out a multifactorial exploration of the symptoms that it produces, its course and possible predisposing factors, as well as whether therapeutic exercise programs were able to neutralize the effects of persistent fatigue. Among the aims of this Doctoral Thesis are: 1) To clarify the prevalence of the symptoms produced by fatigue in long-term breast cancer survivors; 2) To analyze if the level of fatigue after finishing oncology treatment is related to higher levels of persistent fatigue and its relationship with both functional and psychological disturbances in these patients ≥ 5 years later, besides identifying potential predictors of persistent fatigue; 3) To evaluate whether the favourable effects obtained by means of therapeutic exercise programs in breast cancer survivors continue to be maintained over time; 4) To determine if the level of physical activity influences the level of persistent fatigue, without considering the participation in a therapeutic exercise program. The results of this Doctoral Thesis point out: 1) More than 40% of the long-term breast cancer survivors suffer from cancer-related fatigue ≥ 5 years beyond cancer diagnosis and those who suffer from higher levels of fatigue have lower quality of life, higher level of pain, worse mood state, and lower physical fitness; 2) Women with higher levels of fatigue after finishing oncology treatment report not only greater levels of persistent fatigue but also higher levels of pain and mood disturbances, as well as lower physical fitness condition and quality of life. Furthermore, persistent fatigue can be partially explained (69.2%) by ‘sadness/depression’, ‘global health status’, ‘physical activity level’, and ‘type of treatment received’; 3) The positive effects of therapeutic exercise programs in breast cancer survivors are not maintained over time; and 4) More than half of the women (66.25%) could be considered as inactive ≥ 5 years after completing the therapeutic exercise program, and that inactivity is accompanied by higher levels of persistent fatigue. This Thesis Dissertation helps not only to understand the need to evaluate the long-term breast cancer survivors health status who suffer from higher levels of fatigue, but also to identify modifiable predictors that could reduce the impact of this symptom on the health of these patients, thereby establishing long-term intervention key points. Finally, it also highlights the need to perform physical activity habitually throughout the disease-free phase in order to significantly cushion the multiple effects derived from the disease itself and its treatments.