Endorectal ultrasound in the identification of rectal tumors for transanal endoscopic surgery: factors influencing its accuracy

Abstract

Endorectal ultrasound (ERUS) is considered the technique of choice for selecting patients for transanal endoscopic surgery (TEM). The aim of this study was to evaluate the accuracy of ERUS in patients with rectal tumors who later underwent TEM, and to analyze the factors that influence this accuracy. Observational study including prospective data collection of patients with rectal tumors undergoing TEM with curative intent between June 2004 and May 2016. Preoperative staging by EUS (uT) was correlated with the pathology results after TEM (pT). The accuracy of the EUS was evaluated and a series of variables (tumor morphology, height, lesion size, quadrant, definitive pathology, the surgeon assessing the ERUS, and waiting time from the date of the ERUS until surgery) were analyzed as possible predictors of diagnostic accuracy. Six hundred and fifty-one patients underwent TEM, of whom 495 met the inclusion criteria. The overall accuracy of EUS was 78%, sensitivity 83.78%, specificity 20%, PPV 91.3%, and NPV 11%. Forty patients (8.08%) were understaged and 50 (10.9%) were overstaged. In the multivariate analysis, the surgeon's experience emerged as the most important predictor of accuracy (p < 0.001; OR 2.75, 95% CI 1.681-4.512). The EUS was less accurate with larger lesions (p = 0.004; OR 0.219, 95% CI 0.137-0.349) and when the definitive diagnosis was adenocarcinoma (p < 0.001; OR 0.84, 95% CI 0.746-0.946). ERUS accuracy rates are variable and there is a possibility of understaging and overstaging that must be taken into consideration. This accuracy is dependent on the operator's experience as well on lesion size; in addition, it is lower for lesions shown to be cancers in the final pathology report.

Long‐term outcomes of endoscopic submucosal dissection and transanal endoscopic microsurgery for the treatment of rectal tumors

“…The good outcomes in the ESD group were also associated with fact that the lesions in this group were staged using magnifying chromoendoscopy, while the lesions in the TEM group were staged by ERUS. ERUS is considered a good method for evaluating early rectal cancer and has been increasingly adopted, 26 but recent studies suggest that it might not be so precise, with accuracy ranging from 36% to 78% 27–30 . On the other hand, accuracy of magnifying chromoendoscopy for predicting depth of invasion of early colorectal cancer is reported to be higher than 80%, 31–36 reaching 96.4% in our experience 37 .…”

Role of Endoscopic Ultrasound in Diagnosis of Rectal and Perirectal Lesions

“…According to Soh et al [18], EUS had a low diagnostic accuracy of 50% for subepithelial tumors (5/10), 75% for non-subepithelial tumors (15/20), and an overall diagnostic accuracy of 67% (20/30) for rectal and perirectal lesion. And according to Serra-Aracil et al [19], the overall accuracy of EUS was 78%, with 83.78% sensitivity, 20% specificity, 91.30% PPV, and 11% NPV. Forty patients (8.08%) were under staged, whereas 50 (10.90%) were over staged.…”

Transanal Local Excision or Endoscopic Dissection for Benign and Large Lesions of the Rectum

“…Yet, even today, the technique's reliability in the routine does not come close to a sufficient standard to replace the definitive histological examination, 6 if not in limited single-center experiences. 7 8 9 Similarly, the use of different diagnostic techniques such as magnetic resonance imaging (MRI) allowed a better accuracy 10 11 in the discrimination between N+ and N− and low reliability in T staging for <T2 12 nor did the different classifications based on endoscopic imaging. The characteristics of surface morphology of large colonic lesions have attempted to predict submucosal invasive cancer.…”