Evaluation of Prognostic Factors and Trastuzumab-based Treatments in HER2/Neu-positive Metastatic Gastric Cancer.

To determine the efficacy of trastuzumab-based treatment in patients with HER2/neu-positive metastatic gastric cancer. Observational study. Department of Medical Oncology, Istanbul University, Institute of Oncology, Istanbul, Turkey, between January 2014 and December 2020. The clinicopathological characteristic and treatment data of patients with HER2/neu-positive metastatic gastric cancer were recorded retrospectively. Kaplan-Meier analysis was performed to compare the chemotherapy regimens. Sixty-three patients were included in the study. The average age was 61. Female patients accounted for 27% of the total, while male patients accounted for 73%. De novo metastatic cases accounted for 44 (69.8%) of the total number of patients. The median survival time was 13.6 (8-19.3) months. Complete response was 6.3%, partial response was 39.7%, and the stable response was 9.5% with trastuzumab-based chemotherapy. The overall survival (p= 0.45) and progression-free survival (p=0.893) were similar for different chemotherapy regimens. The grade 1-2 to grade 3-4 toxicity ratio was 79.6% and 20.6%, respectively. The patients' performance (p<0.001) and the number of metastatic sites (p=0.001) were both shown to be unfavourable predictive variables for OS in multivariate analysis. The addition of taxane to trastuzumab-based combinations (with platinum and fluoropyrimidine) did not affect overall and progression-free survival in this research. Three or more metastatic sites and poor performance status were found as the unfavourable prognostic variables for overall survival. Gastric cancer, Trastuzumab, Chemotherapy, Prognostic factors.