[Endosonographic staging of rectal tumors]

Source of errors in the evaluation of early rectal cancer by endoluminal ultrasonography

PURPOSE

Although preoperative evaluation of early rectal cancers can be done by endoluminal sonography and by means of colonoscopic findings, it is still controversial whether endoluminal sonography can effectively discriminate mucosal from submucosal lesions. This study was performed to verify objective causes of errors in the evaluation of early rectal cancer (T0/1) using a review of videotaped endoluminal sonography images.

METHODS

Eighty-nine patients with suspected early rectal cancer on endoluminal sonography were included. Two different scanners with appropriate probes were used according to tumor location, i.e., transrectal ultrasonography was used to scan up to 8 cm of the rectum above the anal verge, whereas endoscopic ultrasonography was used to assess higher lesions. Endoluminal sonography images were correlated with histologic infiltration and were reevaluated carefully to identify sources of errors.

RESULTS

Sensitivity and specificity were 83.1 and 96.5 percent, respectively, for tumor staging, whereas sensitivity was very low compared with specificity (16.7 vs. 90.2 percent) for metastatic lymph nodes. Endoluminal sonography images showed irregularity of the underlying tumor border (P < 0.01) and hypoechoic blurring or cutoff of the inner and outer hypoechoic layers (P < 0.001), all of which closely correlated with histologic infiltration of tumor cells. Overstaging occurred more than twice as often as understaging in tumor reevaluation (14 vs. 5 occurrences). In contrast to tumors, lymph nodes showed a similar amount of both overstaging (four cases) and understaging (five cases). The sources of errors were summarized as five types: false instrumentation, interpretive errors, anatomic defects, imaging failure, and inevitable errors.

CONCLUSIONS

Because false instrumentation, interpretive errors, and anatomic defects were considered preventable, 23 (82.1 percent) of the 28 errors might have been avoided. Therefore, a clear image by endoluminal sonography can effectively distinguish mucosal from submucosal lesions in early rectal cancer.

The use of rectal ultrasound for the correct diagnosis and treatment of rectal villous tumors

BACKGROUND

One of the difficulties associated with surgery for rectal villous tumors (RVT) is the finding of invasive adenocarcinoma after transanal excision (TAE) and the possible need for more radical procedures or adjuvant therapy. Improved preoperative evaluation may eliminate this dilemma. The aim of our study was to evaluate the role of transrectal ultrasound (TRUS) in establishing the correct diagnosis of RVT.

METHODS

All patients with biopsy proven RVT, who were referred for TAE, underwent preoperative TRUS in addition to the routine evaluation. If invasion beyond the submucosa was suspected by TRUS, multiple biopsies were taken before any surgical intervention in order to exclude invasive cancer. If no invasion was noted, biopsies were avoided and a TAE was performed. The final pathology results were compared with both the preoperative diagnosis and TRUS results.

RESULTS

Thirty-five patients (19 female, 16 male; mean age 67.5 years, range 36 to 88) were studied. The mean distance of the distal extent of the lesion above the anal verge was 5.8 cm (1.5 to 6). In 27 patients, the tumor was limited to the submucosa (uT0, uT1) on TRUS and, therefore, TAE was performed. In 26 of 27 patients (96%), pathology examination confirmed the presence of RVT without evidence of malignancy. One patient was found to have invasion of the muscularis propria and required postoperative radiation therapy. In 8 patients (23%), TRUS showed extension beyond the submucosa; 3 of these patients had uT2 lesions, 4 had uT3 tumors, and 1 had perirectal nodes. These 8 patients underwent repeated biopsies with the finding of invasive adenocarcinoma in 7. Two patients underwent abdominoperineal resection, 3 had a low anterior resection, and 3 had a TAE. Final pathology confirmed the preoperative diagnosis of invasive adenocarcinoma in 7 patients. In the 1 patient with a uT2 lesion and negative biopsies, the final diagnosis was RVT with no evidence of malignancy.

CONCLUSIONS

Preoperative TRUS provides an accurate diagnosis of RVT. In conjunction with TRUS-directed biopsies, directed management of these tumors could be achieved.

Endosonographic examination of gastrointestinal anastomoses with suspected locoregional tumor recurrence

BACKGROUND

Endoscopic ultrasound is considered one of the best tools for the preoperative staging of esophageal, gastric, and rectal carcinoma. Depending on the individual investigator, the sensitivity of preoperative tumor staging by endosonography of the upper gastrointestinal tract (GEUS) is 80-92% for gastric carcinoma and 86-95% for esophageal carcinoma. However, the sensitivity and specificity of endosonography for the staging of lymph node metastases is less accurate. The accuracy of rectal endosonography (REUS) is approximately 90% for tumor assessment and approximately 80% for the detection of lymph node metastases. In this study, we address the question of whether endosonography enables the surgeon to distinguish scar tissue, which is rather homogeneous and echo-rich, from changes such as an anastomositis or a locoregional tumor recurrence, which are typically non-inhomogeneous and echo-poor.

METHODS

During a 24-months period, we studied patients enrolled in a special tumor follow-up care program by either upper gastrointestinal (GEUS, n = 37 patients) or rectal endosonography (REUS, n = 49 patients) for exclusion of a locoregional tumor recurrence. In each patient, local tumor recurrence was suspected because of either medical history, clinical examination, or other diagnostic procedures.

RESULTS

As in previous studies, our retrospective analysis revealed that endosonography has a high sensitivity in the detection of local tumor recurrences (>90%) for both GEUS and REUS.

CONCLUSION

Endosonography is a highly accurate means of detecting local tumor recurrence.