As a medical oncologist, one of the first threats I inform new patients about during the informed consent process for cancer treatment is how vulnerable they now are to infections. Cancer weakens the immune system, and common therapies on which we rely, such as chemotherapy, further diminish the body’s ability to protect itself from infections. An upper respiratory infection might be an inconvenience for a healthy adult. For an immunocompromised person living with cancer, it could be fatal.
Most people don’t understand how important antibiotics are to cancer care. My entire ability to treat a patient’s cancer is predicated on the idea that antibiotics will both cure and prevent opportunistic bacterial infections throughout their course of care. It is no exaggeration when I say that antibiotics have helped nearly every cancer patient whom I have successfully cared for during their hospital admission for complications of their cancer or treatment.
And yet, when I was invited to be part of a joint task force and research team focused on antimicrobial resistance among cancer patients, I hesitated. My first thought was, “That’s not a cancer specialist’s problem, that’s an infectious disease problem.”
Antibiotic-resistant bacteria, colloquially known as “superbugs,” are a fast-emerging global threat that are now associated with more than 4.5 million deaths annually. They cause complex infections that cannot be treated with standard antibiotics, and they are more common in immunocompromised patients. Antibiotic resistance is one of the greatest threats to modern medicine, but there’s very little discussion so far of what it means for cancer care. Part of the problem is that in the hyper-specialized worlds of medicine and health policy, superbugs are the remit of infectious disease specialists while cancer occupies the realm of non-communicable diseases.
After reflecting on how dependent my patients are on antibiotics, I stepped out of my silo and joined the research team. What we have found is alarming and should serve as a wake-up call to oncologists everywhere to join the global fight against antimicrobial resistance.
Our first study, published in Cancer Medicine, examined data from more than 4 million admissions across 168 hospitals in the U.S. and found that hospitalized cancer patients were 1.5 to 2 times more likely to have an antibiotic-resistant infection compared with hospitalized patients who did not have cancer. Several of the drug-resistant bacteria for which cancer patients were at increased risk, according to our study, have been flagged by the World Health Organization as “priority pathogens,” meaning they pose a notable threat to global public health, and there are few new drugs in development against them.
In our second study, recently published in Lancet Oncology, we observed a similar elevated risk in the outpatient setting. In our analysis of more than 1.5 million bacterial isolates collected from 198 outpatient facilities in the U.S., we found that rates for antimicrobial resistance among priority pathogens were up to 3 times higher in cancer patients compared with non-cancer patients who received care in the outpatient setting; for the multidrug-resistant bacteria Pseudomonas aeruginosa, the rate was five times greater among patients with cancer.
Also of concern is that our data showed that cancer patients had significantly higher rates of infections caused by bacteria that were resistant to a class of antibiotics known as fluoroquinolones. That’s troubling, as the American Society of Clinical Oncology and the Infectious Diseases Society of America recommend prophylactically administering fluoroquinolones when patients have an elevated risk of developing neutropenia, a complication that results in reduced numbers of specific white blood cells, and is a relatively common side effect associated with chemotherapy.
Superbugs and cancer are both global challenges that disproportionately affect those in low- and middle-income countries, and the dangerous synergies our studies identified between cancer and antibiotic resistance are likely amplified many times over in countries with fewer resources.
There are basic precautions we can take to mitigate the threat. Clinicians, patients, and their families need to adhere to infection control and prevention guidelines, as well as recommended immunization guidelines. Handwashing, disinfecting shared surfaces, and vigilantly monitoring for symptoms of an infection are some of the best ways to protect vulnerable patients from infections.
Governments and drugmakers also need to work toward revitalizing research and development into new antibiotics and faster, more precise diagnostics for bacterial infections. There are approximately 50 new antibiotic candidates in clinical development compared with more than 1,500 cancer treatments and vaccine candidates in development. Without effective antibiotics, we’ll never fully reap the benefits of immunotherapies, precision medicines, and other recent advances in cancer care.
On a more fundamental level, cancer providers need to speak up and spotlight the threat antibiotic-resistant infections pose to our patients. Treatment guidelines pertaining to antibiotic-resistant infections among cancer patients continue to lag. The most recent American Society of Clinical Oncology and Infectious Diseases Society of America Clinical Practice Guideline Update for management of neutropenic fever in adult cancer patients was in 2018. Very few cancer societies address, let alone prioritize, antibiotic resistance as a global public health crisis to promote with their members. And there is scant published research on antibiotic resistance and its current and long-term implications for cancer care; the research that does exist tends to be in infectious disease journals, not oncology journals.
A cancer patient and an infectious disease patient are often the same person, and our siloed systems artificially bifurcate how clinicians approach each ailment. A holistic approach to the care of our patients requires that we equally advocate for newer cancer therapies at the same time as we join the fight against antimicrobial resistance.
We urgently need to build an evidence base that can better inform how we care for our patients in the age of superbugs, and we need to draw on experts from across disciplines to develop strategies for educating patients on this emerging risk. In other words, we need to step out of our silos.
Yehoda Martei is a medical oncologist, cancer outcomes researcher, and an assistant professor of Medicine at the University of Pennsylvania. The opinions expressed in this article do not necessarily represent those of the University of Pennsylvania Health System or the Perelman School of Medicine.
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