The role of intrarectal ultrasound (IRUS) in staging of rectal cancer and detection of extrarectal pathology

Intrarectal Ultrasound (IRUS) is rapidly becoming an effective tool in the staging of rectal cancer. Twenty-nine consecutive patients with adenocarcinoma of the rectum underwent both CT scanning and IRUS in the preoperative assessment of rectal cancer in an effort to correlate IRUS staging with surgical pathology, correlate tumor staging comparing IRUS with CT scan, and determine incidence of extrarectal pathology by IRUS. Patients were reviewed as to IRUS stage, results of CT scan, TNM stage of extirpated tumor, incidence of genitourinary pathology, and sonographic result of preoperative radiotherapy (RT). The mean age of all patients was 69 years; there were 25 males and four females. Twenty-four patients underwent proctectomy with either low pelvic anastomosis or end stoma; five underwent local surgical therapy. Thirteen patients received preoperative RT. CT scan correlated poorly with IRUS staging of tumors penetrating the muscularis propria. IRUS overstaged 40 per cent, understaged 5 per cent, and correctly staged 55 per cent of patients when compared with pathological specimens. Eleven of the 25 males (44 per cent) had abnormal prostates by IRUS. Five (20%) had further urologic intervention, resulting in two prostatic cancers found. Our data suggests that CT scan staging correlated poorly with IRUS staging. CT poorly determines depth of rectal tumor wall invasion. IRUS correlated well with pathology and understaged 5 per cent of patients before surgery. Genitourinary abnormalities were detected in a significant number of patients. IRUS is an effective modality for preoperative staging of rectal cancer. A significant number of genitourinary abnormalities may be anticipated when employing preoperative IRUS. Staging with IRUS allows for effective surgical decision-making and strategies for preoperative adjuvant therapy.