P-0284 Importance of Endorectal Sonography in Rectal Cancer Staging (Poster Presentation)

Abstract

ABSTRACT Introduction The staging of rectal cancer is a crucial part of the complex therapy of this form of cancer. The purpose of this study was to assess the diagnostic validity of three- dimensional (3D) endoluminal ultrasound at preoperative 3D staging of rectal cancer (uT). Methods The preoperative staging of rectal cancer has been made at our Surgical Department for 20 years. The method of 3D endosonography was introduced in 2000. During the period from 8/2005 to 12/2010, the 3D endorectal sonography was used in 236 examination of rectal tumour. Malignant rectal cancer was diagnosed in 156 patients and that method was indicated in 80 cases for adenomatous or villous rectal polypus. Endosonography shows 5 layers of the rectal wall – three hyperechogenic layers (mucous, submucous, periproctal adipose tissue) and two hypoechogenic layers (muscularis mucosae, muscularis propria). Tumours of uT1 stage show the infiltrated mucous layer and submucosa. Tumours of uT2 stage infiltrate the muscularis propria, uT3 carcinomas infiltrate the whole rectal wall up to the periproctal adipose tissue, and uT4 carcinomas infiltrate the periproctal adipose tissue or adjacent organs. All our patients underwent surgical intervention. Endorectal approach by using an operation rectoscope was applied by patients with uT1 and uT2 stage who had tumour of 3 cm in diameter of G1-2 grading. All surgical samples were examined by one histopathologist. Results The preoperative rectal cancer staging by 3D endorectal sonography correlated with histopathology in 136 patients (87.5%). The up-staging by 3D endorectal sonography was seen in 16 patients (10.3%). The up-staging was assessed in 7 cases of histopathologic pT1 stage evaluated by endorectal sonography as uT2, in 6 patients with histopathologic stage pT2 evaluated as uT3 and in 3 cases of histopathologic pT3 stage evaluated by endorectal sonography as uT4. The down-staging at 3D endorectal sonography was seen in 4 patients (2.3%). It was histopathologic stage pT4 evaluated by endorectal sonography as uT3-T4. Conclusion The data indicate that the preoperative staging of malignant rectal cancer by 3D endorectal sonography results in 100% detection only in the pT1 stage. In pT2 stage the staging accuracy of 3D endorectal sonography was the lowest at 75%, but in stage pT3 it was 85.5% and in pT4 it was 94%. According to our experience, the interpretation of findings obtained by 3D endorectal sonography at limits of T2 – T3 and T3 – T4 is the most difficult. The reason for this is the peripheral reactive fibrous and inflammatory reaction near the tumor tissue often involves the adjacent rectal wall and it echogenecity is the same as the tumor and this results in the overestimation of invasion depth during endorectal sonography of cancer.