ABSTRACT
OBJECTIVES: Endoscopic Ultrasonography (EUS) is widely used to diagnose upper gastrointestinal tract disease. In recent, it is reported that EUS is also goood diagnostic method to assess depth of invasion through rectal wall and lymph node involvement of rectal cancer. We performed EUS in preoperative rectal cancer patients and compared to post operative histologic findings to evaluate EUS diagnostic accuracy for rectal cancer staging system METHODS: 51 patients with rectal cancer were performed with EUS. They were diagnosed by endoscopic biopsy from August 1994 to June 1996 at Kangbuk Samsung Hospital. Their ages were 28 to 78 (mean: 55 years) and the male to female ratio was 2 : 1 (34/17). Olympus GF-UM3, EU-M3 EUS and 7.5/12 MHz transducer were utilized. EUS was performed by the deaerated water filling method. We have analyzed between preoperative EUS findings and postoperative biopsy findings in order to evaluate the accuracy of EUS. The accuracy of EUS was signified by percentage. RESULTS: 1) Endoscopic ultrasonographic accuracy for assessment of wall invasion of rectal cancer was as follows ; The accuracy of mucosal cancer was 50% (patient numbers of EUS diagnosis/patient numbers of histologic diagnosis: 2/4). Submucosal cancer was 100% (1/1). Muscularis propria cancer was 44% (4/9). The accuracy with penetration to subserosa (or perirectal fat tissue) was 97% (33/34). The accuracy with invasion to adjacent organ was 33% (1/3). The overall accuracy rate was 80% (41/51). 2) EUS accuracy of lymph node metastasis in rectal cancer was ; The sensitivity was 90% (patient numbers of EUS diagnosis/patient numbers of histologic diagnosis: 28/31). The specificity was 60% (12/20). 3) EUS diagnosis of modified Duke classification was ; The accuracy of A stage was 80% (patient numbers of EUS diagnosis/patient numbers of histologic dagnosis: 4/5). B1 stage was 60% (4/8). B2 stage was 33% (1/3). C1 stage was 0% (0/3). C2 stage was 86%(25/28). D stage was 33% (1/3). The overall accuracy rate was 69% (35/51). CONCLUSION: EUS is useful method to assess rectal cancer invasion through rectal wall and lymph node involvement. However, further refinements in instruments and the techniques is required for more improving diagnostic accuracy.