Lung cancer and the Gut-microbiota-lung Axis: emerging evidence and potential clinical implications

Lung cancer remains the leading cause of cancer-related deaths globally, with a 5-years survival rate of only around 20%. Merging cohort and Mendelian-randomization studies indicate that gut dysbiosis is associated with—though not yet proven to cause—an elevated risk and worse prognosis of non-small-cell lung cancer. Lower fecal abundance of butyrate producers such as Faecalibacterium prausnitzii and expansion of Enterobacteriaceae correlate with reduced systemic CD8 + T-cell infiltration and shorter progression-free survival during immune-checkpoint blockade. Antibiotic exposure within 30 days before anti-PD-1 initiation is consistently linked to diminished objective response and overall survival in retrospective cohorts, whereas supplementation with butyrogenic probiotics or fecal microbiota transplantation from responders restores therapeutic efficacy in pre-clinical models. This review integrates epidemiological, mechanistic and clinical data to clarify the current evidence, identify gaps and outline the steps needed to translate gut–lung-axis research into safe, effective adjunctive therapies for patients with lung cancer.