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

OBJECTIVE: To determine the efficacy of trastuzumab-based treatment in patients with HER2/neu-positive metastatic gastric cancer. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Department of Medical Oncology, Istanbul University, Institute of Oncology, Istanbul, Turkey, between January 2014 and December 2020. METHODOLOGY: 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. RESULTS: 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. CONCLUSION: 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. KEY WORDS: Gastric cancer, Trastuzumab, Chemotherapy, Prognostic factors.