Local preoperative staging of rectal cancer with endorectal ultrasonography and phased-array magnetic resonance imaging, comparison with histologic findings

INTRODUCTION:Preoperative clinical staging of rectal tumors is very important to allow surgeons makeinformed decisions about the types of surgeries that should be performed. Endorectalultrasonography (ERUS) is one of the tools that has been commonly used in clinical stagingof rectal tumors. The aim of this study was to evaluate the accuracy of the preoperative rectaltumor staging using endorectal ultrasonography in comparison with the phased-arraymagnetic resonance imaging and the postoperative histopathological staging.METHODS:Fourty-three patients (23 males, 20 females) who have biopsy proven rectal tumorunderwent both MRI and ERUS examinations before surgery. And 26 patient underwentpreoperative neoadjuvan chemoradiotherapy and 17 of them underwent MRI and ERUS afterpreoperative neoadjuvan chemoradiotherapy. All patients were evaluated to determine thediagnostic accuracy of depth of transmural tumor invasion and lymph node metastases.Imaging results were correlated with histopathological findings regarded as the goldstandard and both modalities were compared in terms of predicting preoperative localstaging of rectal carcinoma. The sensitivity, spesificity, the negative predictive value (NPV)and the positive predictive value (PPV) of MRI and ERUS findings were measured 95%confidence interval. Also agreement between two observers were assessed by means of theKappa statistic.RESULT:The accuracy of ERUS for T stage after chemo-radiation was 76,5%. In the prediction ofextramural invasion with ERUS, the sensitivity was 100,0%, the specificity was 33,3%,the PPV was 73,3%, the NPV was 100,0%. The majority of overstaging occurred inpatients with ERUS T3 tumors, eventually found to have pathological pT0?pT2staging. In thedetection of perirectal lymph node metastases, the accuracy of ERUS 70,6% . The sensitivity50,0%, the specificty 81,8 %, the PPV was 60,0 %, the NPV was 75,0%. Statistically, therewas poor correlation between pathologic and radiologic extramural invasion and lymph nodestaging(?=0,39 and ?=0,33)CONCLUSIONS : ERUS provides a good accuracy rate for staging rectal cancer after neoadjuvantchemoradiation. Also ERUS is an objective, convenient, and highly accurate tool forpreoperative rectal tumor staging, thus helping surgeons to determine the appropriatetreatment modalities.