Discussion
Gastric cancer is one of the most common human malignant tumors. Epidemiological investigations have provided evidence that gastric carcinogenesis is a complex, multistep and multifactorial event (15). Considering that reactive oxygen species (ROS) are capable of changing a number of cellular events involved in the cancer process by which cancer cells escape the immune system, the status of oxidative stress and immunity response may be a crucial factor in the development of gastric cancer. Despite continuous progress in the development of conventional therapies such as surgery, chemotherapy, and radiotherapy, as well as novel target-protein-based cancer therapy, gastric cancer is still the second highest cause of