# Gut Microbiome Profiles in Association with Breast Cancer Recurrence and Mortality

> **NIH NIH R03** · VANDERBILT UNIVERSITY MEDICAL CENTER · 2024 · $175,000

## Abstract

PROJECT SUMMARY
 While breast cancer prognosis has substantially improved over the last three decades, recurrence
remains a significant risk, particularly for African American patients and patients from low- and middle-income
countries (LMIC). Novel interventions are needed to prevent cancer recurrence and reduce mortality. Increasing
evidence suggests that the gut microbiota may influence the efficacy of cancer therapy, thus impacting cancer
prognosis. On the other hand, cancer treatment, particularly chemotherapy, may lead to dysbiosis of the gut
microbiota and changes in bacterial metabolic activities. These alterations might persist beyond the time of
treatment, resulting in a reduction in beneficial bacteria, thereby influencing long-term breast cancer outcomes.
Thus, gut microbiota is a potential target to improve the efficacy of cancer treatment and long-term health
outcomes in breast cancer patients. However, the impact of cancer therapy, particularly chemotherapy, on gut
microbiota after the completion of therapy, as well as the influence of gut microbiota on long-term breast
cancer survival, is largely unknown. To address these knowledge gaps, we propose conducting a pilot study to
evaluate the associations of pre- and post-chemotherapy and -radiotherapy gut microbiome profiles with breast
cancer recurrence and mortality (Aim 1). We will use the existing pre-systematic treatment gut microbiome
data from 364 cases and perform shotgun metagenome sequencing on 110 post-chemotherapy or/and -
radiotherapy stool samples in the Vietnam Breast Cancer Study (VBCS). We will also investigate the impact of
chemotherapy on the gut microbiome profile (Aim 2). We will examine changes in gut microbial diversity, taxa
abundance, microbial metabolic pathways, and microbiome dysbiosis indexes among 110 breast cancer
patients with paired pre- and post-chemotherapy stool samples. This proposed study will be the first to
evaluate the associations of pre- and post-systemic treatment gut microbiome profiles, as well as their gut
microbiome dysbiosis indexes, with the risk of breast cancer recurrence and mortality at 5 years post-
diagnosis. Findings from this proposed study will support the launch of a full-scale study to fully understand the
role of gut microbiota in breast cancer outcomes, eventually leading to the development of a microbial-based
intervention to improve long-term cancer outcomes and quality of life for survivors.

## Key facts

- **NIH application ID:** 10951958
- **Project number:** 1R03CA292953-01
- **Recipient organization:** VANDERBILT UNIVERSITY MEDICAL CENTER
- **Principal Investigator:** Sang Minh Nguyen
- **Activity code:** R03 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $175,000
- **Award type:** 1
- **Project period:** 2024-08-01 → 2026-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10951958

## Citation

> US National Institutes of Health, RePORTER application 10951958, Gut Microbiome Profiles in Association with Breast Cancer Recurrence and Mortality (1R03CA292953-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10951958. Licensed CC0.

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