Antibiotic therapy is associated with decreased time to cancer recurrence and survival in women with advanced epithelial ovarian cancer (EOC) treated with platinum chemotherapy, according to a new study by researchers in the Ob/Gyn & Women’s Health Institute and Lerner Research Institute.
“Studies in non-gynecologic cancers have demonstrated that antibiotics may negatively affect treatment outcomes. Since response to platinum chemotherapy is the biggest predictor of survival for women with EOC, identifying factors that lead to resistance is essential to improving survival. It is important for us to know if doing something we think is helpful, like prescribing antibiotics, could hurt a patient’s chances of survival by making them more resistant to treatment,” says Laura Chambers, DO, a fellow in the Division of Gynecologic Oncology and corresponding author on the study published in Gynecologic Oncology. “That’s exactly what we found.”
A significant survival difference
In the retrospective study, the researchers studied 424 women with newly diagnosed stage III or IV EOC who underwent cytoreductive surgery and then platinum chemotherapy from 2009 to 2015. They found that women who received antibiotics had worse outcomes compared to those who did not receive antibiotics. They were prescribed for a variety of reasons, including urinary tract infections, pneumonia/upper respiratory infections and more.
More than 86 percent of patients who received antibiotics during chemotherapy experienced cancer recurrence, compared to roughly 74 percent of patients who did not received antibiotics. Antibiotic use was also associated with a significant reduction in progression-free and overall survival, with patients who received antibiotics living on average nearly 17 fewer months than patients who did not receive antibiotics (45.6 months versus 62.4 months, respectively).
“There was a survival difference of approximately 17 months, which is a lot of time considering new drugs struggle to demonstrate overall survival benefits,” added Roberto Vargas, MD, a practicing oncologist in the Division of Gynecologic Oncology, researcher in Department of Translational Hematology & Oncology Research and co-author on the study. “If we are judicious with our antibiotic treatments, particularly during chemotherapy, we could potentially give the gift of time to patients and their families.”
Dr. Vargas continued, “I can’t remember the last study in which there was a survival difference of this magnitude. However, the fact that antibiotic use was associated with worse outcomes did not come as a surprise.”
Looking for a connection: antibiotic-associated gut dysbiosis
Previous research has demonstrated that antibiotic treatment increases resistance to platinum chemotherapy and immunotherapy in patients with melanoma, lung cancer and renal cell carcinoma. Its effects on EOC had not been known until now.
While Dr. Vargas believes that more prospective studies are needed, these findings suggest that doctors should be cautious in their use of antibiotics in EOC patients undergoing platinum chemotherapy, including in acute care scenarios such as emergency rooms, who are most likely see EOC patients and be faced with making initial decisions to start antibiotics.
Why antibiotic use and platinum chemotherapy resistance might be linked is still considered a hypothesis, although Dr. Chambers believes it may be related to the effect these medications have on the gut microbiome, which she is currently studying in preclinical models.
“Over the last decade, there’s been an increasing focus on the gut microbiome and its involvement in overall health and disease, including cancer,” said Dr. Chambers. “We think that the bacteria may act as a mediator for certain types of cancer treatments, including immunotherapy.”