The intricate interplay of stress, quality of life, and gut microbiota in newly diagnosed breast cancer patients

In a recent study published in Scientific Reports, researchers investigated the relationship between quality of life (QOL), stress, and gut microbiota in patients newly diagnosed with breast cancer.

They found that the microbial composition of the gut was strongly linked to the stress and QOL in the studied cohort. Further, the microbial species belonging to Alcaligenaceae and Sutterella were enriched in the gut of patients with greater distress scores, and those from Streptococcaceae and Streptococcus were prevalent in those with lower distress scores.

Background

Breast cancer in women is the most commonly diagnosed malignancy and a leading cause of mortality worldwide. While the evolution of diagnosis and treatment modalities for breast cancer in recent years has helped improve clinical outcomes in patients, the overall experience may be stressful and impact the quality of their physical, mental, social, and emotional health.

The human microbiota is a collection of microbes colonizing various organs of the body, especially the gut, which are known to be associated with various aspects of health and disease, including the susceptibility to breast cancer.

While the composition of the gut microbiota varies among individuals, evidence suggests that an imbalance in the diversity and specificity of these microbes may significantly impact the immunity, response to chemotherapy, and metastatic potential of cancer in breast cancer patients. Additionally, the composition of the gut microbiota and the use of probiotics are also shown to affect the levels of fatigue, stress, depression, and anxiety in these patients.

However, there’s a shortage of studies exploring the role of gut microbiota in modulating stress and QOL in patients newly diagnosed with breast cancer. Therefore, the present study addressed this gap to identify a potential relationship among these parameters.

About the study

This prospective observational study included 82 female patients above 20 years of age diagnosed with breast cancer stage 0 (2.4%), I (23.2%), II (58.5%), III (11%), or IV (4.9%) between May 2019 and May 2022. The mean age of the participants was 45.7 years. Exclusion criteria of the study were the presence of recurrent breast cancer or a history of mental illness.

Among the patients, 78 were operated surgically, 71 received chemotherapy, 34 received radiotherapy, and 49 received hormone therapy. At the first admission for cancer treatment, the fecal samples of these patients were collected to assess the gut microbiota.

To classify the microorganisms present in the samples, 16S ribosomal ribonucleic acid (rRNA) was isolated and amplified using quantitative polymerase chain reaction (qPCR). Metagenomic analysis was conducted further. The alpha- and beta-diversity of the samples were analyzed. Statistical analysis included the determination of the mean and standard deviation (SD), as well as the use of Student’s t-test and analysis of variance (ANOVA).

Additionally, the functional assessment of chronic illness therapy-breast (FACT-B) questionnaire, which evaluates the physical, social, emotional, and functional wellbeing of individuals, was used to evaluate the QOL, and a distress thermometer (DT) was used to measure their distress levels.

Results and discussion

The mean FACT-B score of the participants was found to be 104.5, and the mean DT score was 4.43. Forty-four patients showed moderate to severe distress as per DT scores (greater than five), majorly caused by emotional concerns such as nervousness and worry and practical concerns such as treatment decisions. The DT scores did not vary significantly with the stage of disease or treatment modality.

Through the analysis of the microbial samples, the researchers identified the most abundant bacterial taxa in the study groups. Individuals with higher DT scores had significantly abundant cells of Alcaligenaceae family (p = 0.017) and Sutterella genus (p = 0.017). Interestingly, Alcaligenaceae is reported in previous literature to be associated with inflammatory disease, depression, and various other cancers.

On the other hand, individuals with lower DT scores had a microbiota significantly rich in Streptococcaceae family (p = 0.028) and Streptococcus (p = 0.023) genus. However, further research is required to clarify the potential role of these bacteria in disease progression and QOL of breast cancer patients.

While patients with depression reported an abundance of Christensenellaceae, Ruminococcaceae, Fecalibacterium, Coprococcus, Obeum, Prausnitzii, and Plebeius, those without depression had a microbiota rich in Eubacterium and Dolichum. Further, various microbial families, genera, and species associated with high or low physical, social, emotional, and functional wellbeing were identified in the study groups.

Although the present study does not establish a causative relationship between depression and the gut microbiome, the DT scores assessed in the study emphasize how healthcare professionals need to provide psychological counseling to patients and educate them about the risks and benefits of various treatment options as well as support them with coping strategies.

Conclusion

This is the first study investigating the relationship between distress, QOL, and gut microbiota composition among newly diagnosed breast cancer patients. It highlights the need to consider gut microbiota composition as an important factor while treating breast cancer patients.

Further research is required to understand the mechanisms underlying these associations to potentially develop biomarkers and effective probiotic-based interventions for improved clinical outcomes in breast cancer patients.