Effects of Antibiotics on First-line Immunotherapy in Patients With Recurrent or Metastatic Nasopharyngeal Carcinoma.

Immunotherapy combined with chemotherapy has become the first-line treatment for recurrent or metastatic nasopharyngeal carcinoma (RM-NPC). However, the impact of antibiotic (ATB) use on the efficacy of immunotherapy in RM-NPC remains unclear. A total of 200 patients with RM-NPC who started first-line immunotherapy between October 2021 and September 2023 were included. Forty-six patients received ATB within 60 days before and 42 days after the first infusion of immunotherapy (group ATB+), and the remaining 154 patients were in group ATB-. The median progression-free survival (PFS) times of the ATB+ and ATB- groups were 11.20 and 19.87 months, respectively ( P = 0.061). The 2-year overall survival (OS) rates of the ATB+ and ATB- groups were 52.6% and 76.7%, respectively ( P = 0.001). In multivariate analysis, ATB use was significantly associated with worse OS (hazard ratio = 2.549, P = 0.002). No significant differences were observed between the 2 groups in terms of grade 3+ treatment-related adverse events. ATB use in RM-NPC may reduce the effectiveness of first-line immunotherapy.