[Results of preoperative staging using endosonography in rectal cancer]

The latest reports using transrectal ultrasound (TRUS) for the preoperative staging of rectal cancer show a diagnostic accuracy between 78 and 97% with regard to the local spread of disease, and between 62 and 86% for the diagnosis of lymph node metastasis. The correct choice of surgery depends on correct preoperative staging, as does the indication for any preoperative neoadjuvant treatment. The aim of this study was to evaluate the diagnostic precision of the method used by the authors since 1993 by comparing the preoperative transrectal ultrasound stage (uTMN) with the postoperative histological stage (pTNM). In addition, the study aimed to assess whether some anatomic and pathological characteristics of the neoplasm (differentiation, type of growth and presence of peritumoral inflammatory reaction) influenced the diagnostic precision of transrectal ultrasonography.

Forty-two patients with a preoperative histological diagnosis of adenocarcinoma localised in the rectal segment, extending up to 10 cm from the dentate line, undergoing radical surgical were selected from the group of patients with middle-lower rectal cancer studied preoperatively with TRUS. Preoperative TRUS was carried out in 42 cases by a single examiner. Anatomic and pathological examination of the removed portion was performed by examiners who were not familiar with the preoperative ultrasonographic diagnosis.

In this study TRUS showed a diagnostic accuracy of 81% in the study of T and 71.4% in the study of N. In line with other studies, the most frequent diagnostic error was the overstaging of stage T2 tumours. Moreover, the presence of a peritumoral inflammatory reaction was found to be the only variable that significantly influenced the diagnostic accuracy of TRUS.

TRUS was found to be a valid instrument for the preoperative staging of rectal cancer even in this preliminary study limited to 42 cases, in particular with regard to wall invasion. The limits of this method are linked to the presence of phenomena producing a situation of local infection (recent biopsies, radiotherapy, peritumoral inflammatory infiltrate) given that this prevented the correct visualisation of the layers of the rectal wall. As a result, this may limit its use in the re-staging of patients undergoing preoperative radiotherapy.