Breast cancer patients’ microbiome may hold key to avoiding damaging heart side-effects of cancer therapies

New research suggests that a healthy microbiome before chemotherapy could help protect breast cancer patients against heart damage, or cardiotoxicity, as a result of cancer therapy.

Researchers found that specific bacteria in patients’ gut microbiome correlated with heart health biomarkers that suggest they are at greater risk of heart damage during chemotherapy.

“To allow cancer survivors healthier lives, we need to find new ways to protect them from the long-term side-effects of chemotherapy. This study is one of the first to ask whether the microbiome could play a role in how well patients’ hearts fare during chemotherapy,” explained Doctor Athos Antoniades, head of research and development at Stremble Ventures LTD who is leading the multi-omics, including the gut microbiome DNA sequencing for this project.

“We saw a clear association between some specific genus of gut bacteria and cardiac biomarkers that suggest patients are at greater risk of heart damage during chemotherapy,” he added.

“While further research is needed, it does give us the tantalizing hope that tailored probiotics could play a role in protecting patients against the harmful effects of cancer treatment in future,” Dr. Antoniades said.

The study recruited 98 women over the age of 60 who were diagnosed with breast cancer from three clinical treatment centers across Europe: the Bank of Cyprus Oncology Center, Cyprus; the National and Kapodistrian University of Athens and the Greece and European Institute of Oncology, Italy.

The women received ultrasound heart scans, also known as echocardiograms, to test heart function, and had blood tests to test for biomarkers known to put women at a greater risk of heart damage during treatment. Genetic sequencing was used to profile all the bacteria in the gut of the patients before they received cancer treatment.

This study is part of a wider project called CARDIOCARE which will allow the research to expand to a larger study of 600 women to confirm the finding. This work offers the hope that tailored probiotics could be used to help protect women from the heart side-effects of chemotherapy in future.

The new research is being presented at European Cardio-Oncology 2025, a scientific congress of the European Society of Cardiology. The study is part of a wider project called CARDIOCARE.

Researchers found that specific bacteria, called Bacteroides, were prevalent in patients that also had heart health biomarkers, specifically LVGLS, NTproBNP and Troponin I, which indicate that patients are more susceptible to heart damage during cancer treatment. The gut bacteria profile of these patients was similar to those found in patients with heart failure.

Bacteroidaceae are a family of very common gut bacteria that can be beneficial to health, but can also be harmful to health when their populations are dysregulated. They can cause infections in other areas of the body and can have a role in driving inflammation.

“We are already following up these 98 patients after chemotherapy, and are expanding the research project to all 600 patients already enrolled in the CARDIOCARE clinical trial,” Dr. Antoniades concluded.

Heart damage, or cardiotoxicity, is a relatively common side-effect of many cancer treatments, including chemotherapy. As treatments for breast cancer improve and more patients recover, greater numbers of patients are living with the long-term side-effects of treatment.

New research suggests that a healthy microbiome before chemotherapy could help protect breast cancer patients against heart damage, or cardiotoxicity, as a result of cancer therapy.

Researchers found that specific bacteria in patients’ gut microbiome correlated with heart health biomarkers that suggest they are at greater risk of heart damage during chemotherapy.

“To allow cancer survivors healthier lives, we need to find new ways to protect them from the long-term side-effects of chemotherapy. This study is one of the first to ask whether the microbiome could play a role in how well patients’ hearts fare during chemotherapy,” explained Doctor Athos Antoniades, head of research and development at Stremble Ventures LTD who is leading the multi-omics, including the gut microbiome DNA sequencing for this project.

“We saw a clear association between some specific genus of gut bacteria and cardiac biomarkers that suggest patients are at greater risk of heart damage during chemotherapy,” he added.

“While further research is needed, it does give us the tantalizing hope that tailored probiotics could play a role in protecting patients against the harmful effects of cancer treatment in future,” Dr. Antoniades said.

The study recruited 98 women over the age of 60 who were diagnosed with breast cancer from three clinical treatment centers across Europe: the Bank of Cyprus Oncology Center, Cyprus; the National and Kapodistrian University of Athens and the Greece and European Institute of Oncology, Italy.

The women received ultrasound heart scans, also known as echocardiograms, to test heart function, and had blood tests to test for biomarkers known to put women at a greater risk of heart damage during treatment. Genetic sequencing was used to profile all the bacteria in the gut of the patients before they received cancer treatment.

This study is part of a wider project called CARDIOCARE which will allow the research to expand to a larger study of 600 women to confirm the finding. This work offers the hope that tailored probiotics could be used to help protect women from the heart side-effects of chemotherapy in future.

The new research is being presented at European Cardio-Oncology 2025, a scientific congress of the European Society of Cardiology. The study is part of a wider project called CARDIOCARE.

Researchers found that specific bacteria, called Bacteroides, were prevalent in patients that also had heart health biomarkers, specifically LVGLS, NTproBNP and Troponin I, which indicate that patients are more susceptible to heart damage during cancer treatment. The gut bacteria profile of these patients was similar to those found in patients with heart failure.

Bacteroidaceae are a family of very common gut bacteria that can be beneficial to health, but can also be harmful to health when their populations are dysregulated. They can cause infections in other areas of the body and can have a role in driving inflammation.

“We are already following up these 98 patients after chemotherapy, and are expanding the research project to all 600 patients already enrolled in the CARDIOCARE clinical trial,” Dr. Antoniades concluded.

Heart damage, or cardiotoxicity, is a relatively common side-effect of many cancer treatments, including chemotherapy. As treatments for breast cancer improve and more patients recover, greater numbers of patients are living with the long-term side-effects of treatment.