The Human Microbiome and Fatigue in Individuals with Breast Cancer

Abstract

Fatigue is a common and distressing symptom for individuals with breast cancer, but interventions to mitigate fatigue are limited as the underlying mechanisms contributing to fatigue development are not fully understood. One pathway previously linked with fatigue in healthy and select chronically ill populations is the human microbiome. Yet, while fatigue has been correlated with the human microbiome in certain populations, the association between the human microbiome and fatigue in individuals with cancer is less clear. Thus, the purpose of this dissertation was to enhance understanding of the relationship between the human microbiome and fatigue in individuals with breast cancer. This goal was achieved through synthesizing current knowledge on the correlation between the gut microbiome and fatigue across cancer types as well as the completion of novel research on the association between the oral microbiome and fatigue in individuals with breast cancer.The specific chapters of this dissertation are as follows: Chapter 1 - an introduction of the problem and contextual background; Chapter 2 – a systematic review on the association between the gut microbiome and fatigue in individuals with cancer; Chapter 3 – a cross-sectional quantitative study on the oral microbiome and the psychoneurological symptom cluster in individuals with breast cancer; Chapter 4 – a longitudinal quantitative study on fatigue, co-occurring symptoms, and the oral microbiome in women with breast cancer; Chapter 5 – a synthesis of the findings and recommendations for future research. In short, this dissertation identified correlations between the gut microbiome and fatigue across cancer types as well as found evidence for an association between the oral microbiome and fatigue in individuals with breast cancer. Correlations between other psychoneurological symptoms and the oral microbiome were also identified. Future research should consider multi-omics approaches with larger sample sizes to better elucidate the mechanistic underpinnings relating the human microbiome to fatigue in individuals with breast cancer as this could provide insight into the potential utility of the human microbiome for targeted symptom management interventions.