Impact of first-line nivolumab plus chemotherapy on conversion surgery rate for advanced gastric/esophagogastric junction cancer

Background : Systemic chemotherapy plus nivolumab is a first-line treatment in unresectable advanced gastric cancer; however, the ideal determination of conversion surgery eligibility remains unclear. This study identified predictors and prognostic factors related to conversion surgery, including the effects of first-line nivolumab. Methods : This single-institutional retrospective study included 129 patients who received systemic chemotherapy for advanced gastric or esophagogastric junction cancer. Data were compared between treatments with and without first-line nivolumab and 1:2 propensity score matching was performed to adjust for baseline differences. Results : Conversion surgery was performed in 17 (13.2%) patients. With nivolumab plus chemotherapy, the conversion surgery rate was 36.8% (7/19). In a multivariate analysis, the combination of nivolumab as first-line treatment was an independent predictor of conversion surgery both before and after matching. Minimally invasive surgery was performed on seven patients, six of whom were patients receiving nivolumab with R0 resection. An Eastern Cooperative Oncology Group Performance Status of ≥1, presence of liver metastasis, and conversion surgery were independent prognostic factors in advanced gastric cancer. Conclusions : First-line nivolumab combination chemotherapy improved eligibility for conversion surgery in advanced gastric or esophagogastric junction cancer. Understanding the prognostic factors identified herein may help guide treatment selection and improve patient outcomes.