Relationship of early tumor shrinkage and depth of response with the prognosis and treatment effect of trastuzumab combined with chemotherapy as first-line treatment in advanced gastric cancer patients with epidermal growth factor receptor 2 positive

Abstract

Objective: To explore the relationship of early tumor shrinkage (ETS) and depth of response (DpR) with the prognosis and treatment effect of trastuzumab combined with chemotherapy as first-line treatment in advanced gastric cancer with epidermal growth factor receptor 2 (HER-2) positive. Methods: We retrospectively analyzed the clinical and pathological data of 23 patients with metastatic gastric adenocarcinoma diagnosed by imaging in The Second Affiliated Hospital of Zhejiang University School of Medicine from January 1st, 2008 to December 31th, 2017. Kaplan-Meier method and the log-rank test were used for the survival analysis. Cox regression was used to analyze the factors associated with prognosis. Results: The objective response rate (ORR) of the 23 patients was 43.5% and the disease control rate (DCR) was 82.6%. Univariate analysis showed the median progress-free survival (mPFS) of ETS≥20% and ETS<20% were 13.0 months and 4.5 months, respectively, with statistical significance (P<0.001). The median overall survival (mOS) of ETS≥20% and ETS<20% were 26.8 months and 10.1 months, respectively, with statistical significance (P<0.001). The median progress-free survival (mPFS) of DpR≥15% and DpR<15% were 13.0 months and 4.5 months, respectively, with statistical significance (P=0.001). The median overall survival (mOS) of DpR≥15% and DpR<15% were 26.8 months and 9.5 months, respectively, with statistical significance (P<0.001). Multivariable Cox regression analysis revealed ETS was an independent factor of PFS (P=0.030), tumor site and Eastern Cooperative Oncology Group (ECOG) score were independent factors of OS (P<0.05). Conclusion: ETS and DpR might be used to predict the treatment efficacy and prognosis of trastuzumab combined with chemotherapy as the first-line treatment of HER-2 positive gastric cancer.