Can Antibiotics Increase the Chances of Cancer Coming Back?
- A recent study by researchers at Stanford Medicine says that the use of multiple antibiotics may be associated with a specific type of breast cancer, triple negative breast cancer, returning after treatment (recurrence).
- Researchers demonstrated that a correlation between antibiotic use and breast cancer recurrence might exist, but they cannot definitively say that antibiotics cause recurrence at this time.
- Triple-negative breast cancer accounts for 20% of all breast cancers. It's an aggressive form of the disease and is associated with shorter overall survival.
- You should never avoid the use of antibiotics if they were prescribed by a physician, but it’s important to discuss the real need of antibiotic use as well.
Now, patients should not panic if they have already been treated with antibiotics after their breast cancer diagnosis, says Dr. Allison Kurian, professor of Medicine, Epidemiology and Population Health at Stanford University School of Medicine and one of the authors of the study.Read More
The Gut MicrobiomeAccording to Harvard University, the microbiome consists of microbes that are both helpful and potentially harmful. Most are symbiotic (where both the human body and microbiota benefit) and some, in smaller numbers, are pathogenic (promoting disease). In a healthy body, pathogenic and symbiotic microbiota coexist without problems. But if there is a disturbance in that balance brought on by infectious illnesses, certain diets, or the prolonged use of antibiotics or other bacteria-destroying medications dysbiosis occurs, stopping these normal interactions. As a result, the body may become more susceptible to disease, like cancer. Cleveland Clinic Dietician Krista Maruschak explains what we know about the gut microbiome, overall health, and cancer.
Can I Improve My Gut Microbiome?Experts say that there are several things you can do to keep your gut microbiota healthy, balanced and functioning optimally. Those tips include:
- Eating healthy
- Staying active or becoming physically active
- Stopping smoking
- Only taking medications prescribed by your doctors, especially antibiotics
What Is Triple-Negative Breast Cancer?Triple-negative breast cancer is one of the most aggressive forms of the disease and accounts for about 10-20% of all breast cancers. Once you've been diagnosed with breast cancer, your doctor will review your pathology report and the results of any imaging tests to understand the specifics of your tumor. Using a tissue sample from your breast biopsy or using your tumor if you've already undergone surgery, your medical team determines your breast cancer type.
This information helps your doctor decide which treatment options are most appropriate for you.
This specific type of breast cancer is called triple-negative because it does not have any of the main drivers of breast cancer: the estrogen receptor, the progesterone receptor, and the HER2 protein receptor.
What this means is that hormonal therapy can't be used because the cancer cells lack these receptors. It also means that therapies targeted at HER2 will not be an effective treatment option.
Triple-negative breast cancer is more common in people younger than age 50 and is more likely to be diagnosed in Black women and Hispanic women. The majority of breast cancers diagnosed in people with an inherited BRCA gene mutation are triple-negative.
About the Study
A total of 772 women who were diagnosed between January 2000 and May 2014 and treated at Stanford Health Care or Palo Alto Medical Foundation were studied.
All women had triple-negative breast cancer, and all of them received antibiotics within three years after their cancer diagnosis.
Over the course of the study, 20% of patients who were not prescribed antimicrobials passed away, while 23% of patients who had never received antimicrobials died.
The risk imposed by antimicrobial use is, therefore, relatively small. However, for every additional antimicrobial drug that was taken, there was a significant reduction in the likelihood of survival in triple-negative breast cancer patients.
Each additional antibiotic increased the risk of death between 5% and 18% relative to patients who weren't prescribed antibiotics.
Dr. Julia Ransohoff, the lead author of the study and a fellow in hematology and medical oncology at the Stanford School of Medicine said that it is important to interpret the findings with caution: “We can't let life-threatening infections go untreated. But this study suggests that we consider how best to treat them without raising the risk of cancer recurrence."
The researchers found that treatment with antimicrobials was associated with a decrease in the numbers of an immune cell called lymphocytes circulating in a patient's blood. Lymphocyte numbers have been shown to correlate with response to treatment and overall survival in people with breast cancer.
There were several drawbacks to the study.
- Many patients did not have access to the current triple-negative breast cancer treatments like immune checkpoint inhibitors because they were diagnosed so long ago.
- The authors confirm that there is a correlation of antibiotic use but they cannot infer causality (causality is the science of cause and effect). For example, there is a correlation between the number of people who drowned by falling into a pool, between 1999 and 2009, and the number of movies that Nicolas Cage appeared. That does not mean that Nicolas Cage presence in films cause those deaths.
- Triple-negative breast cancer is also a unique breast cancer type that is harder to treat and more rare than other types. However, it is also more susceptible to immune attacks. Thus, the link between antibiotic intake and poor survival rates may not be found in other breast cancer types.
Future studies might produce more specific and definitive results concerning individual antibiotics and breast cancer risk by subtype, age of diagnosis or other characteristics.
In the mean time, it’s utterly important that you always discuss option with your healthcare provider. Remember that the doctor is there to help you. They want you to be honest with them so that they can do everything they can to keep you healthy. No matter what you say, it won't be the first time they've heard it. So, feel free to ask them anything about your disease and treatment.
Questions to Ask Your Doctor
- Should I be worried about taking antibiotics if I need them?
- What is the risk if I get an infection that requires antibiotic use?
- What steps can I safely take to improve my gut health?
- How will I be monitored for cancer recurrence?