The value of endorectal ultrasonography in rectal cancer staging

Abstract

Introduction Preoperative staging of rectal cancer is considered essential to select patients adequately for different therapeutic regimes. The aim of the present study was to evaluate the accuracy of endorectal ultrasonography in preoperative staging of rectal cancer. MATERIALS AND METHODS Fifty rectal cancer patients (31 men, 19 women) underwent endorectal ultrasonography with a 7.5-MHz probe. Thirty-eight of these patients had preoperative chemoradiation and in these patients examination was done before and after the radiotherapy treatment. The results of examinations were compared with the histological findings of the resected specimens. RESULTS Histopathology showed 4 stage T0, 3 stage T1, 12 stage T2, 30 stage T3, and one stage T4 tumor. Nodal metastases were seen in 17 patients. The overall accuracy of endorectal ultrasonography for determining the depth of invasion (T stage) was 66% (33/50). The accuracy rate of T1 was 100% (1/1), T2 was 45% (9/20), T3 was 79% (22/28), and T4 was 100% (1/1). Overstaging was 18% (9/50) and understaging 16% (8/50). In staging lymph node metastasis, the overall accuracy rate was 70% (18/25) with 18% (9/50) overstaged and 12% (6/50) understaged. With regard to nodal involvement, sensitivity was 65% and specificity 73%. Regarding penetration of the rectal wall (stages T1 and T2 vs stages T3 and T4 / Dukes' classification A versus B), endorectal sonography showed sensitivity, specificity, and accuracy of 74%, 68%, and 72%, respectively. CONCLUSION Endorectal ultrasonography is a valuable diagnostic modality for rectal cancer staging. It is fast, safe, accurate, well tolerated by the patient and cheap procedure and therefore should be used as a diagnostic modality of the first choice in rectal cancer staging although one must take into consideration possible limitations in cases of preoperative chemoradiation.