Adjuvant and neoadjuvant chemoradiation therapy for primary colorectal cancer

The management of rectal cancer presents substantial challenges. Patients with T3 and/or node-positive rectal cancers are at high risk for local failure and distant metastases (DM). Adjuvant radiation has been shown to decrease local recurrence (LR) rates; however, this local therapy has not been demonstrated to improve survival when compared to surgery alone. In several prospective randomized trials adjuvant chemoradiation with 5-fluorouracil-(5-FU)-based chemotherapy improved LR rates, DM rates, and overall survival (OS). The optimal chemotherapeutic regimen has not been determined; however, studies comparing standard IV bolus 5-FU administration with continuous infusion (CI) 5-FU demonstrated that CI administration was superior. Preoperative therapy has potential advantages over adjuvant therapy such as less acute bowel toxicity and improved sphincter preservation. Preoperative chemoradiation has been shown in several studies to improve LR rates and OS when compared to surgery alone. Our current approach to patients with resectable T3 or N1 cancer in the distal two-thirds of the rectum on preoperative staging is preoperative chemoradiation with planned postoperative chemotherapy. This regimen offers the best chance for local control and disease-free survival while potentially downstaging the tumor and improving sphincter preservation.