ABSTRACT
Background: Preoperative clinical staging of rectal tumors is very important to allow surgeons make informed decisions about the types of surgeries that should be performed. Endorectal ultrasonography (ERUS) is one of the tools that has been commonly used in clinical staging of rectal tumors. The aim of the present study was to evaluate the accuracy of endorectal ultrasonography in preoperative staging of rectal tumors and evaluate the factors that influence on the reliability of endorectal ultrasound staging such as experience of ultrasonographer, Characteristics of the tumor and tumor site (in terms of height) Methods: Fifty-three patients with rectal adenocarcinomas underwent an endorectal ultrasonography evaluation during a period of three years. The evaluation was performed by three surgeons. We compared the endorectal ultrasonography staging with the pathology findings based on the surgical specimens. Patients with preoperative chemoradiation were excluded from the study. Results: Overall accuracy in assessing the level of rectal wall invasion was 55%, with 19% of the tumours overstaged and 26% understaged. Accuracy in assessing nodal involvement in 44 patients treated with radical surgery was 45%, with 41% overstaged and 14% understaged. If focus on experience of ultrasonographer that show learning curve for good progression in accuracy of assessing tumor invasion from 42% in 2005 to 87% in 2007. Accuracy for Characteristics of the tumor that show better progression in accuracy for ulcerative tumor from 25% in 2005, 62% in 2006 and 100% in 2007 but for polypoid tumor that show poorer accuracy rate only 50% for all three years. Whether tumour site (in terms of height) found a significantly poorer accuracy rate for tumours of the distal third (2-6 cm from anal verge) that show accuracy only 48% ,on the other hand significantly better for tumours of the middle third (7-12 cm from anal verge) that show accuracy 62%. Accuracy depended on the tumor stage, ultrasonographer experience , characteristics of the tumor and tumor site (in terms of height). Conclusions: The accuracy of endorectal ultrasonography in assessing the depth of tumor invasion, particularly for early cancers, is lower than previously reported. Endorectal ultrasound is more operator dependent and accuracies improve with experience and characteristics of the tumor and tumor site (in terms of height) that influence on the reliability of accuracy.