According to a study conducted by researchers at Stanford Medicine, women with triple-negative breast cancer who received multiple antibiotic prescriptions within three years of their cancer diagnosis were more likely to experience disease recurrence and to pass away from their cancer than those who took fewer courses of the drugs.
The study found that differences in cancer severity did not have an impact on survival.
The danger significantly rose when each patient received more and different kinds of antibiotic prescriptions.
According to Julia Ransohoff, MD, a fellow in hematology and medical oncology at the Stanford School of Medicine, “each additional antibiotic increased the risk of death between 5% and 18% relative to patients who weren’t prescribed antibiotics.” But it’s important to use caution when interpreting these results.
The researchers studied 772 women who were diagnosed between January 2000 and May 2014 and treated at Stanford Health Care or Palo Alto Medical Foundation.
They found that treatment with antimicrobials (a class of drugs that includes antibiotics to treat bacterial infections and antifungals to treat fungal infections) 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. (Although the researchers studied total antimicrobial prescriptions, 99% of the women in the study who were prescribed antimicrobials received antibiotics.)
The researchers believe the link between antimicrobials and lymphocyte numbers lies in the gut. It’s well established that antibiotic treatment, as well as chemotherapy, can be especially harsh on the bacteria that carpet our intestines — a population of tiny helpers known as the gut microbiome. These bacteria not only help us digest food, but also affect many aspects of our health, including how our immune systems respond to emerging threats like infection or cancers.
