Hypothesis of this study is that increased immunity of primary tumor affects the increased number of lymph node retrieved. This study investigates whether immunity-related cytokine expression on primary tumor, colonic mucosa, and serum is associated with the number of lymph node retrieved in colorectal cancer patients.

Inclusion Criteria:

• 1. Histologically confirmed colorectal cancer 2. Non-metastatic cancer (cTNM I, II, or III) 3. Over 20 years of age 4. Curative resection (R0)

Exclusion Criteria:

• 1. Patient with distant metastasis 2. History of chemotherapy or radiation therapy for malignancy 3. Patient receiving immunosuppressive or anti-inflammatory treatment 4. Hereditory colorectal cancer 5. Preoperative chemoradiation therapy for colorectal cancer 6. Pregnancy 7. Emergency

Colorectal cancer patients diagnosed with clinically TNM I, II, or III stage