Geographic difference in safety and efficacy of systemic chemotherapy for advanced gastric or gastroesophageal carcinoma: a meta-analysis and meta-regression

The standard of chemotherapy regimens for advanced or metastatic gastric cancer and the clinical outcome were heterogeneous in Asian versus non-Asian countries. This study aimed to explore predictors of safety and efficacy of chemotherapy for patients with advanced or metastatic gastric cancer. Treatment group-based meta-analysis and meta-regression were performed to analyze results of randomized trials published since 2005 for advanced or metastatic gastric cancer patients who received systemic chemotherapy as first-line treatment. Data were extracted and synthesized according to the Cochrane guidelines. Twenty-five trials (8 Asian, 17 Western or international) with 56 treatment groups were analyzed. Asian trials reported a lower percentage of gastroesophageal junctional carcinoma, higher percentage of diffuse-type histology, and more frequent use of second-line chemotherapy. Meta-analysis revealed significant heterogeneity both in treatment safety (grade 3-4 neutropenia and diarrhea) and efficacy [6-month progression-free survival (PFS) and 1-year overall survival (OS)]. Meta-regression analyses indicate that Asian trials are associated with an 8.2% lower incidence of grade 3-4 neutropenia and 2.1% lower incidence of grade 3-4 diarrhea. A lower percentage of patients with gastroesophageal junction carcinoma and the use of combination regimens predicted better PFS. The use of second-line chemotherapy predicts better 1-year OS, which will increase by 10% for every 10% increase in patients who received second-line chemotherapy. Geographic region (Asian vs. non-Asian) is an independent predictor of safety in systemic therapy for gastric cancer.