Introduction: Endorectal ultrasound (EU) is the most important examination for pretherapeutic stratification of primary rectal tumors. Preoperative histology and endosonography determine the therapeutic strategy by using the criteria of depth of infiltration (uT) and lymph node status (uN).
Methods: The effectiveness of endoluminal ultrasound in the preoperative differentiation between locally restricted tumors (adenomas and "low-risk" carcinomas, uT0/1, G1-2) and advanced rectal carcinomas (uT3) was assessed in a retrospective study of 284 patients. In the examination period (UZ) from 3/94 to 12/97 (UZ I) 104 patients (group 1) were examined with a 7-MHz endoprobe, and from 1/98 to 12/99 (UZ II), 116 (group 2) with a 10-MHz endoprobe. Additionally, in 64 patients (group 3) with an advanced uT3/4 or uN + tumor we compared the accuracy of ultrasound with computed tomography (CT). In this group 32 patients were restaged by EU and CT after preoperative chemoradiation. The results of präoperative endorectal ultrasound were correlated with the postoperative histological data.
Results: Concerning the whole period (UZ I and II) we achieved a total hit rate of 83.6% for adenomas and "low-risk" carcinomas (uT0/1, G1/2) by EU (79.8% in UZ I, 87.1% in UZ II). For advanced rectal carcinoma (> or = uT3) we found a total accuracy of 87.3% (82.7% in UZ I, 91.4% in UZ II). In 62 cases endosonographic lymph node status was correlated with postoperative histology during UZ II, with a hit rate of 64.5%. In group 3 (n = 64), in 32 patients without preoperative chemoradiation we found an accuracy for depth infiltration of 93% (EU) and 82% (CT). Concerning lymph node status there was a correlation of 57% (EU) and 64% (CT). After preoperative chemoradiation (n = 32) we found an accuracy of 91% (EU) and 73% (CT) for depth infiltration--for lymph node status 70% (EU) and 82% (CT).
Conclusions: High accuracy in endoluminal ultrasound leads to a secure and differentiated stratification of therapy in primary rectal tumors. The hit rate concerning depth of infiltration is higher for EU than for CT both before and after chemoradiation, but not regarding lymph node status.