A study on the impact of antibiotics on the efficacy and prognosis of advanced lung cancer patients undergoing immune checkpoint inhibitor therapy

<bold>Background:</bold> ICIs significantly improve advanced lung cancer treatment outcomes. This study explores the impact of antibiotics on these patients' response and survival. <bold>Methods:</bold> Analyzed medical records of 631 patients treated with ICIs at West China Hospital, Sichuan University, from December 2018 to June 2023, focusing on those receiving antibiotics around ICI treatment time. <bold>Results:</bold> Most patients had non-small cell lung cancer (74.8%), treated mainly with immunotherapy and chemotherapy (72.9%). Cephalosporins were the predominant antibiotics. Antibiotics use within three months before ICI initiation was linked to lower disease control (odds ratio 0.479, 95% CI 0.260–0.880, p = 0.018) and shorter PFS and OS than non-users (median PFS: 9.9 vs. 12.7 months, p < 0.015; median OS: 26 vs. 36 months, p < 0.031). Multivariate analysis showed worse PFS and OS in antibiotic users (PFS: HR 1.293, 95% CI 1.036–1.612, p = 0.023; OS: HR 1.348, 95% CI 1.007–1.806, p = 0.045), especially with cephalosporins before ICI treatment (OS: HR 1.773, 95% CI 1.216–2.584, p = 0.003). <bold>Conclusion:</bold> Antibiotics, especially cephalosporins, may negatively affect advanced lung cancer patients' response and prognosis on ICI therapy. This underscores the importance of cautious antibiotic use.