Gut bacteria changes linked to chemotherapy-induced weight gain in women with breast cancer
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Key takeaways:
- Women who received chemotherapy only gained an average of 0.15% total mass per month.
- Chemotherapy resulted in signs of inflammation and significant gut bacteria changes.
Chemotherapy-induced changes to gut bacteria appeared associated with unhealthy weight gain among a cohort of women with breast cancer, according to study results published in BMC Medicine.
The findings suggest the gut microbiome may be a target for intervention to prevent chemotherapy-dependent anthropometric changes, researchers concluded.
Rationale and methodology
Patients with early-stage breast cancer who undergo chemotherapy are at increased risk for metabolic disease and weight gain.
This may lead to increased morbidity and reduced quality of life during survivorship, according to John Walker, MD, PhD, head of medical oncology for northern Alberta at Cross Cancer Institute in Canada, and colleagues.
“We aimed to analyze changes within the gastrointestinal microbiome of [women with early-stage breast cancer] treated with and without chemotherapy to investigate a potential relationship with dysbiosis ... and resultant anthropomorphic changes,” Walker and colleagues wrote.
Investigators conducted an a priori analysis that included serially collected stool and plasma samples from 40 women with early-stage breast cancer who either underwent surgery alone (n = 4), surgery and endocrine therapy (n = 8), surgery and chemotherapy (n = 10), or surgery and chemotherapy followed by endocrine therapy (n = 18).
Researchers assessed gut microbiota through metagenomic comparison of stool samples.
They used proteomic analysis of plasma and measurement of fecal calprotectin to evaluate inflammatory biomarkers, and they investigated body composition by dual-energy X-ray absorptiometry to determine biomass indices.
Findings
Overall, results showed women aged younger than 60 years experienced weight gain relative to baseline weight, with a total mass per month increase of 0.085. Those aged 60 years or older experienced a relative reduction in weight of 0.11 (P = .047).
Premenopausal women experienced a significant increase in weight, with a ratio change of total mass per month of 0.18, whereas postmenopausal women experienced a ratio decrease of 0.074 (P = .011).
Women treated with chemotherapy only experienced a mean gain of 0.15% total mass per month, whereas those who received endocrine therapy only experienced a mean loss of 0.19% total mass per month.
Women who underwent chemotherapy also exhibited signs of inflammation and significant alterations in the number and variety of gut bacteria.
“Changes in the bacterial populations within the gut directly correlate with unhealthy weight gain and increased body fat composition in [patients with breast cancer] who were treated with chemotherapy,” Walker said in a press release.
Researchers observed a significant increase in the ratio of total mass per month between android to gynoid fat with a ratio of 0.0045 among patients treated with endocrine therapy only vs. a ratio of 0.0041 among patients treated with chemotherapy only (P = .027).
Implications
“Treatment with chemotherapy, but not endocrine therapy, results in a transient rise in circulating pro-inflammatory cytokines and chemokines, as well as a significant increase in fecal calprotectin levels, which indeed indicates a connection between post-chemotherapy gut microbiota change and inflammation,” Walker and colleagues wrote. “This illuminates a potential mechanism by which chemotherapy could result in weight gain in breast cancer survivorship, and a possible target of future treatments designed to improve long-term patient outcomes.”
References:
- Damage to gut bacteria linked with chemo-induced weight gain in breast cancer patients (press release). Available at: https://www.ualberta.ca/folio/2023/07/damage-to-gut-bacteria-linked-with-chemo-induced-weight-gain-in-breast-cancer-patients.html. Published July 11, 2023. Accessed Aug. 14, 2023.
- Walker J, et al. BMC Med. 2023;doi:10.1186/s12916-023-02751-8.
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