Background:

1. . The incidence and mortality of colon cancer are high in China and in the world.
2. . The treatment of many patients in the real world is not standardized, and there are problems such as over-treatment or under-treatment. To explore the adjuvant treatment of colon cancer in the Chinese population, this study will retrospectively analyze real-world data on adjuvant therapy for colon cancer in Chinese patients after radical surgery.

The purpose of research:

1. . Current status of adjuvant therapy for stage II-III colon cancer in the real world: chemotherapy regimen, chemotherapy time, efficacy, safety, etc.
2. . Comparison of efficacy and safety of different adjuvant chemotherapy time (<3 months vs. >=3 months) in high-risk stage II and III colon cancer patients in the real world
3. . Comparison of efficacy and safety of different adjuvant chemotherapy regimens (XELOX vs. FOLFOX) in high-risk stage II and III colon cancer patients in the real world

Inclusion Criteria:

• Patients who are sick after January 2010
• Age is older than 18
• Surgical pathology confirmed TNM stage II-III (AJCC 7th edition) colon cancer

Exclusion Criteria:

• Combine other tumors
• Pathological information is not clear
• Researchers believe that other reasons are not suitable for enrollment

20000 patients diagnosed with stage II-III colon cancer and undergo radical surgery since January 2010.

The demographic analysis of this study will include but limited in：

• Demographic characteristics (age, gender, height, weight),
• Clinical information (Site, TNM(Tumor, regional lymph Node, Metastasis) staging, CEA(Carcinoembryonic Antigen), imaging findings, patient ECOG(Eastern Cooperative Oncology Group)score, PS(Performance Status) score),
• Pathology information (MMR(Mismatch Repair) status, RAS status, BRAF status, HER2 status, Lymph node, Number of detections, Nerve infiltration, Vascular invasion, Histological type, etc.)