Antibiotic Treatment Improves the Efficacy of Oxaliplatin-Based Therapy as First-Line Chemotherapy for Patients with Advanced Gastric Cancer: A Retrospective Study

Hiroo Imai, Ken Saijo, Keigo Komine, Reio Ueta, Ryunosuke Numakura, Shonosuke Wakayama, Sho Umegaki, Sakura Hiraide, Yoshufumi Kawamura, Yuki Kasahara, Kota Ohuchi, Masahiro Takahashi, Shin Takahashi, Hidekazu Shirota, Masanobu Takahashi, Chikashi Ishioka Department of Medical Oncology, Tohoku University Hospital, Sendai, 980-8575, JapanCorrespondence: Chikashi Ishioka, Department of Medical Oncology, Tohoku University Hospital, 4-1, Seiryo-machi, Aobaku, Sendai, 980-8575, Japan, Tel +81 227178543, Fax +81 227178548, Email chikashi@tohoku.ac.jpPurpose: One of the first-line treatment for gastric cancer patients is oxaliplatin, and the efficacy of this chemotherapeutic can be attenuated by the microbiome. In this study, we retrospectively evaluated whether treatment with antibiotics improved the efficacy of oxaliplatin-based chemotherapy in patients with advanced gastric cancer.Patients and Methods: Fifty-four patients were assigned to the antibiotic-treated group and 35 to the antibiotic-untreated group.Results: The response rate of oxaliplatin-based chemotherapy in the antibiotic-treated and antibiotic-untreated groups was 66.7% and 41.4%, respectively (p = 0.038). The median progression-free survival after oxaliplatin-based chemotherapy in the antibiotic-treated and antibiotic-untreated groups was 8.8 and 5.2 months, respectively (hazard ratio = 0.456, 95% confidence interval = 0.254– 0.819; p = 0.007, Log rank test). Univariate and multivariate analyses revealed that antibiotic treatment was the only clinical parameter that correlated with the response to oxaliplatin.Conclusion: Antibiotic treatment could be used therapeutically to enhance the efficacy of oxaliplatin-based chemotherapy in patients with advanced gastric cancer.Keywords: gastric cancer, chemotherapy, oxaliplatin, antibiotics