This is a prospective, multi-center, open-label, randomised controlled study. The purpose of this study is to evaluate the efficacy and safety of Huaier Granule versus SOX regimen in the postoperative adjuvant treatment of resectable stage II-III gastric cancer.

Gastric cancer (GC) is the second most frequently diagnosed cancer and the second leading cause of cancer related deaths in China. China has a higher mortality/incidence ratio (0.845). For stage II-III GC patients, the current standard treatment is D2 gastrectomy followed by adjuvant chemotherapy. Studies showed the 5-year survival rate of early GC is nearly 95%, while the 1-year recurrence and metastasis rate after surgery is about 50%, and the rate of 2-year is as high as 70%.

Although adjuvant chemotherapy can prevent recurrence, it is inevitable to the appearance of toxic and side effects, which seriously affect the prognosis and quality of life.

Traditional Chinese medicine plays a unique role in enhancement of immune function, detoxification, and synergism of chemoradiotherapy. Huaier granule is an extract from a medicinal fungus. Previous studies have shown that Huaier granule can inhibit the proliferation, angiogenesis, metastasis and invasion of cancer cells, and can reverse the resistance of targeted drugs. Previous studies demonstrated Huaier granule is benefit to resistance to recurrence and metastasis, prolongation of patients' survival, and improvement of quality of life.

In this study, about 30 research centers will participate. Total of 702 participants will be divided into two groups (the Huaier group and the control group) at a ratio of 1:1. The Huaier group will receive Huaier granule as postoperative adjuvant therapy, and the control group will receive SOX regimen. The planned length of patient recruitment enrolment will be 2 years and the total length of visits be 3 years. After enrollment, participants will be visited every 12 weeks (window period ± 14 days) until the end of the study or until the patient withdraws from the study for any reason or dies.

Inclusion Criteria:

• 18-75 years
• Pathologically diagnosed as stage II or III gastric adenocarcinoma (including gastroesophageal junction).
• Receiving radical surgery (R0, D2 resection, more than 16 lymph nodes should be detected) for gastric adenocarcinoma within 2 months prior to enrollment, and not receiving adjuvant treatment.
• Eastern Cooperative Oncology Group (ECOG) performance status from 0 to 2.
• Patients are volunteers, have signed informed consent, and agree to cooperate with investigators in data collection.

Exclusion Criteria:

• Patients had received neoadjuvant therapy.
• Patients who have received or plan to receive targeted therapy and/or immunotherapy。
• Patients allergic to the components of Huaier granules, or avoid to use Huaier granules or use with caution.
• More than two active primary tumors at the same time.
• Patients have not recovered from surgical complications after radical surgery.
• Patients received other Chinese patent medicine with anti-tumor effects.(including but not limited to Huaier Granule, Fufangbanmao Capsule, Huachansu Capsule, Kangai Injection, Pingxiao Table) in the past 1 month.
• Not able to take medication orally cause by difficulty in swallowing, complete or incomplete gastrointestinal obstruction, active bleeding from the gastrointestinal tract, perforation, etc.
• Pregnant or lactating women or women prepare for pregnancy.
• Serious concomitant infection disease.
• Patients with severe psychiatric illness or otherwise diseases are unsuitable for this study according to the judgment by investigators.
• Patients with combined immune disease and receiving immunosuppressive therapy.