01-05-2025
Lancet study shows drug resistance three times higher in cancer patients: What are risk factors?
Infections caused by drug-resistant bacteria are the second leading cause of death in cancer patients, according to a new study published in The Lancet Oncology.
Researchers analysed over 1.5 million pathogens (including over 50,000 from patients with cancer) and found that counts of different antimicrobial-resistant bacteria were between 1.2 and three times greater in outpatients with cancer. The study is significant because it is the first large multi-centre study to quantify AMR bacteria in outpatients with cancer in the US. The bacteria was isolated from adults aged 18 and older, with and without cancer, at 198 outpatient facilities.
The authors have highlighted that the higher counts of AMR bacteria in outpatients with cancer may be due to the use of antibiotics they received during chemotherapy. Study co-author and Fellow of the Infectious Diseases Society of America (FIDSA) Vikas Gupta, says AMR is a growing global health crisis. 'Given the rising rates of AMR globally, more specifically in India, and the increasing drug resistance in vulnerable cancer populations, there should be careful consideration about antibiotic stewardship. This means optimising the use of antibiotics, maximising their efficacy while minimising their harm. Additionally, surveillance efforts to quantify AMR among the cancer-affected population must be undertaken because cancer incidence is projected to increase,' he says.
What the study says
Data was collected between April 1, 2018, and Dec 31, 2022. Across all evaluated pathogens, outpatients with cancer had significantly higher AMR rates per 1,000 pathogen isolates for P aeruginosa and Enterococcus spp compared to non-cancer outpatients.
Why cancer patients are at a higher risk
The results are not unexpected for Dr Abdul Ghafur, consultant in infectious diseases, Apollo Hospital, Chennai and coordinator of the Chennai Declaration on AMR (not attached with the study). 'Cancer patients are at a higher risk because they visit hospitals and healthcare facilities much more frequently than non-cancer patients — before the diagnosis, during the diagnostic process, and later for chemotherapy, radiotherapy, outpatient visits and multiple admissions. With each hospital visit, each admission, and each infection episode, the exposure to antibiotics increases. Naturally, more infections require a higher antibiotic exposure, which means a higher risk of developing drug-resistant bacterial infections,' he says.
Not only a cancer patient's problem, AMR needs global strategy
In cancer patients, the AMR crisis is not a 'silent pandemic' but a very visible, overt pandemic. Since patients are immune-compromised, infections have more severe consequences. 'At our cancer centre, approximately 20% of E. coli and 40–50% of Klebsiella isolates are carbapenem-resistant. Mortality is notably higher in cancer patients infected with drug-resistant bacteria compared to those infected with drug-susceptible strains. This trend holds true in both cancer and non-cancer patients,' says Dr Ghafur, arguing for a well-designed antibiotic policy at the hospital level to reduce mortality.
He also argues for a detailed data collection from patients to formulate an antibiotic use policy. 'In cancer patients, antibiotic therapy must begin without delay — there is no time to wait. 'With the right data, one can make an informed choice to improve patient outcomes,' he adds.
