Accuracy of endorectal ultrasonography in staging locally advanced rectal cancer after preoperative chemoradiation

Abstract

The aim of our study was to determine the accuracy of endorectal ultrasonography (ERUS) in staging locally advanced rectal cancer after preoperative neoadjuvant chemoradiation and to point out the most common reasons for false interpretation. Forty-four patients with locally advanced rectal cancer received neoadjuvant chemoradiation followed by radical surgery. Restaging was done 1-2 weeks before surgery and the results of ERUS staging were compared with histopathology findings of the resected specimen. The accuracy of ERUS for T stage after chemoradiation was 75% (33/44). Overstaging occurred in 18% (8/44) of patients, and 7% (3/44) were understaged. The majority of overstaging occurred in patients with ERUS T3 tumors, eventually found to have pathological pT0-pT2 staging. Five patients (11.4%) had complete histology regression and only one of these patients was staged correctly while others were overstaged. In the detection of perirectal lymph node metastases, ERUS was accurate in 68% of patients (30/44). Twenty percent (9/44) of patients were overstaged and 11% were (5/44) understaged. ERUS provides a good accuracy rate for staging rectal cancer after neoadjuvant chemoradiation. However, it is insufficient in detection of complete pathological response.