Endoscopic Ultrasound (EUS) Staging of Rectal Cancer: Diagnostic Accuracy Before and Following Chemoradiation

Abstract

Background: Staging of rectal cancer is required to determine the type of surgery and the need for preoperative chemoradiation. In a selected population, chemoradiation may induce complete pathological response that enables sphincter-preserving operations. Recently, large studies suggested that EUS might not be as accurate as initially reported. The accuracy of EUS for staging rectal cancer after radiation therapy has not been thoroughly evaluated. Aim: To determine accuracy of EUS staging for rectal cancer before and following chemoradiation. Methods: Patients with rectal cancer who underwent staging by EUS were stratified into two groups. Group I consisted of sixty-six patients who underwent only surgery following EUS staging. Group II consisted of twenty-five patients who had EUS evaluation following chemoradiation, and surgery was performed later. EUS staging was compared to the surgical/pathological staging. Results: In patients who were not treated by preoperative chemoradiation, the accuracy of T-staging was better that the accuracy for N-staging. EUS tended to overstage tumor invasion in both groups. The overall T-Staging of rectal tumors was less accurate following chemoirradiation therapy. In group I most cases of overstaging occurred in patients with pathological T1 stage, whereas in group II most cases of overstaging occurred in patients with pathological T2. Conclusions: Preoperative staging of rectal cancer by EUS is a useful modality to determine the need for chemoradiation. Accuracy is higher for T-stage than for N-stage. The effect of chemoradiation reduces the accuracy of EUS staging. This, however, does not compromise therapeutic decision, given the fact that most cases of overstaging occurred in T2.