The majority of diagnosed cases of gastric cancer are in the middle and late stages, while less than 10% of patients are diagnosed in the early stages in China. The standard treatment strategy for patients with progressive gastric cancer is surgery combined with postoperative adjuvant therapy or preoperative neoadjuvant followed by surgery combined with postoperative adjuvant therapy. Immunotherapy is now recognized as an innovative approach for cancers. It is worth exploring how to best use immunotherapy in neoadjuvant therapy to achieve better clinical benefit. Therefore, this paper reviews the progress of immunotherapy in neoadjuvant therapy for GC. Further studies and the understanding of immune system function by neoadjuvant therapy combined with immunotherapy will help to improve the treatment of gastric cancer.

Objective:To investigate the antioxidant activity of Maca polysaccharides in vitro.Methods:A chemical reaction system was established to explore the scavenging activity of Maca polysaccharides within the concentration range of 0.18-5.00 mg ·ml-1on hydroxyl radicals (·OH),superoxide anion free radicals (O2-·) and DPPH·,and then the total antioxidant capacity was calculated. The protective effects of Maca polysaccharides on H2O2-induced damage in SH-SY5Y cells were determined. SH-SY5Y cells were divided into the control group,H2O2model group and Maca polysaccharide groups(25,50,100 μg·ml-1). In the Maca polysaccharide groups,SH-SY5Y cells were pre-protected by Maca polysaccharides for 24 h, and then incubated in the presence of 300 μmol·L-1H2O2for 6 h. The detection index was SH-SY5Y cell viability detected by MTT assay. Results:Maca polysaccharide within the concentration range of 0.18-5.0 mg·ml-1all exhibited strong scavenging activity on·OH,O2-· and DPPH·in a dose-dependent manner. When the concentration of Maca polysaccharides reached 2.5 mg·ml-1,the scavenging rate was 60.36% for DPPH·,34.66% for O2-·and 36.01% for·OH,the total antioxidant activity was equivalent to 0.179 μmol FeSO4. Maca polysaccharides at the concentration of 25, 50 and 100 μg·ml-1all showed significant protective effects on H2O2-induced injury in SH-SY5Y cells, and the cell survival rate was 61.71 ± 2.45%,61.73 ± 4.51% and 60.98 ± 3.12%, respectively,which were all significantly higher than those in the model group (P < 0.05). Conclusion:Maca polysaccharides has good antioxidant activity,which is worthy of further research and development as a natural antioxidant.