Pilot Study of Oral Microbiome and Psychoneurological Symptom Cluster in Breast Cancer

Women with breast cancer experience high symptom burden from a psychoneurological symptom cluster consisting of fatigue, anxiety, depression, sleep disturbances, and pain. Interventions to manage this symptom cluster are limited as its etiology is not well understood. One system that has been linked with this symptom cluster in both healthy and other chronically ill populations but has not been explored in breast cancer is the oral microbiome.

We examined differences in oral microbiome diversity and composition between women with breast cancer who reported high versus low levels of psychoneurological symptoms.

Oral microbial changes based on bacterial diversity and relative abundance were estimated from 16S rRNA gene sequencing data of oral tongue swabs from 22 women with breast cancer prior to mastectomy. The fatigue, anxiety, depression, sleep disturbance, and pain interference subscales of the Patient-Reported Outcomes Measurement Information System 29 scale were used to calculate the symptom groups.

Observed amplicon sequence variants were lower in the high-symptom group than in the low-symptom group, but no differences between groups were seen in other alpha diversity metrics (Shannon, Inverse Simpson). No differences in beta diversity were found between the high- and low-symptom groups. For differential abundance, three genera were more abundant in the high-symptom group than the low-symptom group: Aggregatibacter, Lautropia, and Prevotellaceae UCG-001.

Preliminary associations were identified between the psychoneurological symptom cluster and oral microbiome diversity and composition. Of the differentially abundant genera, Lautropia has been previously linked with anxiety, and Aggregatibacter has been researched due to its pro-inflammatory potential. As inflammation is posited to influence psychoneurological symptom cluster severity, further research on the relationship between the oral microbiome and the psychoneurological symptom cluster, specifically in relation to potential causal mechanisms, is warranted. Enhanced insight into this relationship could inform targeted interventions to improve the symptom experience for women with breast cancer.