ABSTRACT
AIM: HER2-positive metastatic gastric cancer is still a highly fatal disease despite advances. We aimed to investigate the relationship between HER2/CEP17 ratio and survival in patients with HER2-positive metastatic gastric cancer. METHODS: A total of 99 patients from 8 different centers in Turkey were included in the study. Patients with HER2-positive metastatic gastric cancer and whose HER2/CEP17 ratio was examined were included in the study. Patients were divided into two groups according to HER2/CEP17 values, and survival analysis was performed. RESULTS: The median age was 64 (24-83) years. There were 74 (74.8%) male and 25 (25.2%) female patients. OS in the high HER2/CEP17 ratio group was 21.97 months (95% CI: 16.36-27.58), and in the low ratio group was 16.17 months (95% CI: 10.95-21.38) (p = 0.015). OS was 17.7 months (95% CI: 7.02-28.37) in the high HER2 gene copy number group and 10.13 months (5.55-14.71) in the group with low copy number (p = 0.03). PFS was 10.94 months (95% CI: 7.55-14.33) in the group with high HER2 gene copy number and 7.56 months (4.62-10.49) in the low copy number group (p = 0.06). CONCLUSION: Patients with both high HER2 gene amplification and high HER2/CEP17 ratio had better OS. The PFS of the group with high HER2 gene amplification was also better. To our knowledge, this is the first study in the literature showing that the HER2/CEP17 ratio affects survival in patients with metastatic gastric cancer.