Many patients with local and locally advanced CRC can be treated with surgical removal of the tumor, with no further treatment necessary. The goal of therapy is a cure. Some patients with high-risk Stage II colon cancer and patients with Stage III disease require chemotherapy. In addition, patients with Stage II or III rectal cancer require chemotherapy given in tandem with radiation therapy.

In high-risk patients, chemotherapy is generally administered as adjuvant therapy after the primary therapy of surgery is completed. The adjuvant therapy is designed to lower the risk of cancer recurrence. In patients with larger T4b resectable tumors, neoadjuvant therapy may be administered prior to surgery in some cases, to shrink the tumor. Neoadjuvant and adjuvant chemotherapy and radiation therapy are commonly used to treat larger T3/T4 rectal tumors.