Trastuzumab in combination with chemotherapy for HER2-positive metastatic gastric cancer patients underwent conversion therapy

BACKGROUND: Conversion surgery is a treatment that aims for R0 resection of primary advanced gastric cancers (GCs) that have responded well to systemic chemotherapy. We investigated the role of conversion therapy in initially unresectable metastatic cancer with positive HER2 status that responded to chemotherapy plus trastuzumab. METHODS: A total of 32 metastatic GC patients who underwent systemic chemotherapy plus trastuzumab sequenced by conversion surgery at Zhejiang Cancer Hospital between 2015 and 2020 were retrospectively reviewed. RESULTS: The observed overall survival (OS) and progression-free survival (PFS) for all the patients were 30.2 and 25.1 months, respectively. The 1-year survival rate was 81.25%, and the 1-year PFS rate was 78.13%. Univariate and multivariate analyses demonstrated that liver metastasis (P=0.021), peritoneal metastasis (P=0.047), para-aortic lymph node metastasis (16a1/b2) (P=0.048), macroscopic type 4 (P=0.027), number of noncurative factors (P=0.011), Yoshida et al. category (P=0.021), and inductive chemotherapy cycles (P=0.025) were independent prognostic factors for OS. CONCLUSIONS: HER2-positive patients with potentially resectable disease had a remarkably good prognosis after conversion gastrectomy following trastuzumab treatment. Adequate selection of metastatic GC patients for conversion surgery is recommended.