Background: Human epidermal growth factor receptor 2 (HER2)-positive gastric cancer (GC) is a unique subtype of this disease. Few studies focus on the feasibility of trastuzumab as maintenance or palliative therapy for patients with HER2-positive advanced GC. 
Patients and methods: We retrospectively analyzed the data of 11 patients, evaluated the efficacy and safety of trastuzumab, and attempted to investigate the prognostic factors for trastuzumab treatment. Among the 11 patients, one achieved partial response (PR), six achieved stable disease (SD), and four were evaluated as progressive disease (PD). 
Results: The overall response rate (ORR) was 9.10%, and the disease control rate (DCR) was 63.64%. The median overall survival (OS) was 6.10 months, and the median progression-free survival (PFS) was 6.10 months. A significant association was found between trastuzumab treatment cycles and efficacy (P =0.027), cycles and PFS (P =0.001), and cycles and OS (P =0.005). Among the five patients who accepted more than five cycles of trastuzumab, the median OS and median PFS achieved 23.83 months and 14.67 months, respectively. Moreover, we have found the correlation between tumor marker changes and efficacy (P =0.002) and HER2 status and PFS (P =0.027). No association was found between HER2 status and OS (P =0.597). 
Conclusion: The most common adverse events were left ventricular ejection fraction (LVEF) reduction, fatigue, and anorexia. LVEF reduction was found in seven of 11 patients, but the absolute decline in the LVEF was within 10% from the baseline. The results of this study suggest that trastuzumab is a feasible option as maintenance or palliative therapy for patients with HER2-positive metastatic GC.
Keywords: HER2-positive, gastric cancer, trastuzumab, efficacy, safety