Antibiotic Use Linked to Worse Outcomes in Patients With Gastrointestinal and Liver Cancer on Immune Checkpoint Inhibitors: A Meta-Analysis.

In 30 seconds

This meta-analysis assessed whether antibiotic use was associated with outcomes in adults with gastrointestinal or liver cancers receiving immune checkpoint inhibitors. Across 28 studies, antibiotic use was associated with worse overall survival (HR 1.56; 95% CI: 1.23-1.98) and progression-free survival (HR 1.48; 95% CI: 1.15-1.90), as well as lower disease control. Objective response rate did not differ significantly. Associations varied by cancer type: outcomes were worse in hepatocellular and upper gastrointestinal cancers, while colorectal cancer studies showed improved overall survival. The authors call for prospective validation.

Key findings

• Antibiotic use was associated with worse overall survival (HR 1.56; 95% CI: 1.23-1.98; I2 = 87.3%) and progression-free survival (HR 1.48; 95% CI: 1.15-1.90; I2 = 88.3%).
• Disease control rate was lower with antibiotic use (OR 0.55; 95% CI: 0.33-0.90), while objective response rate showed no significant difference (OR 1.01; 95% CI: 0.78-1.31).
• In colorectal cancer studies, antibiotic use was associated with improved overall survival (HR: 0.58; 95% CI: 0.45-0.75), unlike the worse survival associations reported for hepatocellular and upper gastrointestinal cancers.

Why it matters

Antibiotic exposure may be a clinically relevant correlate of outcomes during immune checkpoint inhibitor therapy, but the differing associations across cancer types caution against assuming a uniform effect. The findings highlight the importance of interpreting antibiotic use in its clinical context and underscore that observed associations do not establish that antibiotics themselves cause poorer outcomes.

What to keep in mind

The analysis pooled studies with substantial heterogeneity for overall and progression-free survival, and the authors state that prospective studies are needed to validate the results.