The Conventional Approach
OC patients receiving platinum-based chemotherapy are immunocompromised and at risk of infection. Broad-spectrum antibiotics are commonly prescribed prophylactically or therapeutically.
Why This Is Counterproductive
Two independent preclinical studies converge on the same conclusion: antibiotic-induced microbiome depletion actively worsens OC outcomes.
1. Increased Tumor Growth and Cisplatin Resistance (Hawkins 2022)
Antibiotic-induced dysbiosis in OC models increased tumor growth AND enhanced cisplatin-induced stemness, enriching cancer stem cell populations. The gut microbiome is required for immune surveillance of OC stem cells. ABX depletes the protective metabolites indole-3-propionic acid (IPA) and indoxyl sulfate — both restored by FMT (hawkins 2022 antibiotics microbiome ovarian cancer).
2. Abolished Chemosensitization (Tian 2026)
Antibiotic depletion of gut microbiota abolished the chemosensitizing effects of Tripterygium glycosides, which work by inducing ferroptosis via Keap1-Nrf2-GPX4 axis inhibition. The microbiome is required for this drug to work (tian 2026 tripterygium lactobacillus cisplatin ovarian cancer).
When This STOP Applies
- OC patient on platinum-based chemotherapy receiving or about to receive broad-spectrum antibiotics
- Prophylactic antibiotic use during chemotherapy cycles
When This STOP Does NOT Apply
- Life-threatening infection requiring immediate antibiotic therapy (infection control takes priority)
- Targeted narrow-spectrum antibiotics for documented pathogen
Alternative Approach
- Use narrowest-spectrum antibiotic possible when antibiotics are medically necessary
- Co-administer probiotics (separated by 2+ hours from antibiotics)
- Consider FMT post-antibiotic course to restore protective metabolite production
- Monitor for microbiome restoration after antibiotic courses before continuing chemotherapy