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

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. Methods 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. Results 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. Conclusions ERUS provides a good accuracy rate for staging rectal cancer after neoadjuvant chemoradiation. However, it is insuficient in detection of complete pathological response.