Journal Article

Antibiotic use and survival from breast cancer: A population-based cohort study in England and Wales

McMenamin, Úna, Cardwell, Chris R., Hippisley-Cox, Julia, Snelling, Andrew JHL, Brady, Aaron J., Coupland, Carol AC, McIntosh, Stuart A., Chen, Daniel Tzu-Hsuan, Hicks, Blánaid, Bannon, Finian J., Atakpa, Emma C., Baxter, Sarah M.

2025

Overview

The role of the gut microbiota in carcinogenesis is increasingly being acknowledged. Recent studies in multiple breast cancer mouse models have found that antibiotics, by altering the gut microbiota, can accelerate tumour growth. In humans, a recent cohort study restricted to triple negative breast cancer showed that breast cancer patients using a greater number of antibiotics had markedly worse survival. These studies have raised concerns about repeated antibiotic use in breast cancer patients. In this Registered Report, we investigated whether breast cancer patients using oral antibiotics had increased breast cancer-specific mortality. In population-based cohorts (n = 44,452), we did not observe a statistically significant association between antibiotic prescriptions after diagnosis and breast cancer-specific mortality (adjusted HR = 1.07 95% CI 0.87, 1.33) apart from prescriptions of 12 or more antibiotics (adjusted HR = 1.62 95% CI 1.31, 2.01). This association was weaker after adjustment for infections (adjusted HR = 1.44 95% 1.14, 1.81), when restricted to antibiotics within five years (adjusted HR = 1.33 95% 0.95, 1.84), and was similar for deaths from other causes (adjusted HR = 1.69 95% 1.19, 2.41). Frequent antibiotic users had higher cancer-specific mortality but the attenuation of associations in sensitivity analyses, and similar findings for other causes of death, suggest this increase may reflect residual confounding. Protocol registration: The Stage 1 protocol for this Registered Report was accepted in principle on 7 November 2023. The protocol, as accepted by the journal, can be found at https://doi.org/10.6084/m9.figshare.24746721.v1 . Studies in mouse models have suggested a link between antibiotic use and breast cancer but epidemiological evidence in human populations is inconsistent. Here, the authors use linked electronic health records from England and Wales to investigate the association between oral antibiotic use and survival in women with breast cancer.

• Publisher: Nature Publishing Group UK,Nature Publishing Group,Nature Portfolio
• Subject: 692/4020/2741/2135 / 692/699/67/1347 / 692/699/67/2324 / 692/700/478/174 / 692/700/565/2194 / Adult / Aged / Animal models / Anti-Bacterial Agents - administration & dosage / Anti-Bacterial Agents - adverse effects / Anti-Bacterial Agents - therapeutic use / Antibiotics / Breast cancer / Breast Neoplasms - drug therapy / Breast Neoplasms - microbiology / Breast Neoplasms - mortality / Cancer therapies / Carcinogenesis / Carcinogens / Cohort analysis / Cohort Studies / Electronic health records / Electronic medical records / England - epidemiology / Epidemiology / Female / Gastrointestinal Microbiome - drug effects / Gut microbiota / Hormone replacement therapy / Human populations / Humanities and Social Sciences / Humans / Hypotheses / Infections / Intestinal microflora / Medical diagnosis / Microbiota / Microorganisms / Middle Aged / Mortality / multidisciplinary / Population (statistical) / Population studies / Prescriptions / Primary care / Registered Report / Science / Science (multidisciplinary) / Sensitivity analysis / Statistical analysis / Survival / Wales - epidemiology