Using this modality, patients with rectal cancer are more accurately staged. The technique consists of examining the rectal tumor and lymph nodes by placing an ultrasound into the rectum. The spread of tumor into the wall of the rectum and into adjacent lymph nodes are then determined. This technique enables proper selection of patients for therapy. Patients found to have early stage disease may be curable by surgical resection alone. In these patients, surgical resection is offered initially and if the final pathology confirms a stage 1 tumor, the patient avoids the potential side effects of radiation and chemotherapy. Patients diagnosed with advanced tumors are offered neoadjuvant radiation and chemotherapy prior to surgery. Neoadjuvant therapy offers the potential benefits of reducing tumor recurrence, improving surgical margins, and decreasing the likelihood of small bowel radiation enteritis which is more likely to occur if radiation is given following surgical resection.