Endorectal ultrasound in the management of patients with malignant rectal polyps

Transanal endoscopic surgery is effective and safe after endoscopic polypectomy of potentially malignant rectal polyps with questionable margins

AIM

To determine the percentage of residual lesion observed in the pathology study of transanal endoscopic surgery (TEM) specimens after endoscopic polypectomy of malignant rectal polyps with questionable margins, and the need for further surgery. Secondary aims: to determine the morbidity and mortality associated with this procedure and to identify the percentage of recurrence after excision by TEM.

METHODS

Observational study with prospective data collection of all patients undergoing TEM after endoscopic polypectomy for malignant rectal polyps or non-invasive high-grade neoplasia, from January 2004 to December 2016. An en bloc full-thickness wall excision of the scar was performed. Variables recorded: histology of TEM specimen, 30-day morbidity and mortality according to the Clavien-Dindo classification, need for salvage surgery and recurrence.

RESULTS

Fifty out of 690 patients undergoing TEM during the study period (36 adenocarcinomas, five non-invasive high-grade neoplasias and 9 neuroendocrine tumors) were included. Post-surgery histology showed residual lesion in 21 (42%) patients: 7 neuroendocrine tumors, 10 adenomas and 4 adenocarcinomas (two pT1, one pT2 and one pT3). The pT2 and pT3 patients (4%) underwent salvage surgery. No recurrence was observed, and mean follow-up was 29.1Â ± 21.6 months. The 30-day morbidity rate was 14%, but 4/7 with Clavien-Dindo grade I.

CONCLUSIONS

After endoscopic polypectomy of malignant rectal polyps with questionable margins, the presence of residual lesion in the pathology study of transanal resection specimens is high. TEM with full-thickness resection of these lesions is an appropriate treatment, allowing disease control and achieving minimal morbidity.

Utility of EUS following endoscopic polypectomy of high-risk rectosigmoid lesions

Background:

The utility of endoscopic ultrasound (EUS) compared with standard white light endoscopy (WLE) following recent polypectomy of high-risk colorectal polyps is unknown.

Objective:

To assess the incremental yield of EUS after endoscopic polypectomy of a high-risk rectal lesion.

Design:

Retrospective cohort.

Setting:

Tertiary referral center.

Materials and Methods:

Patients referred for EUS following attempted endoscopic resection of a high-risk rectal neoplasm, defined as a tubulovillous adenoma, tubular adenoma with high-grade dysplasia, carcinoid, carcinoma in-situ or adenocarcinoma (CA).

Interventions:

Sigmoidoscopy ± mucosal biopsy and EUS ± fine-needle aspiration (FNA) to evaluate for: (1) Residual polyp/tumor in the rectal wall or (2) peritumoral adenopathy.

Main Outcome:

Sensitivity and specificity for detection of residual neoplasia for WLE ± biopsy (WLE/BX) and EUS ± FNA for cancer (CA group) or benign disease (non-CA group). The incremental yield of EUS defined as: (1) Residual intramural neoplasia not present on WLE ± BX and; (2) abnormal peritumoral adenopathy.

Results:

A total of 70 patients (mean age 64 ± 11 years, 61% male) with a final diagnosis of CA (n = 38) and non-CA (n = 32) were identified. There was no difference between the sensitivity and specificity of WLE alone (65% and 84%), WLE with biopsy (71% and 95%), and EUS (59% and 84%), for the detection of residual neoplasia (P > 0.05 for all). EUS identified 3 masses missed by WLE, all in the CA group. A malignant (n = 2) or benign (n = 3) node was identified in 5 (13%) CA patients; EUS-FNA in two showed residual malignancy in one and a reactive lymph node (LN) in one. No LNs were identified in the non-CA patients.

Limitations:

Retrospective design, incomplete follow-up in some patients.

Conclusion:

Following endoscopic polypectomy of high-risk rectal neoplasia, the incremental yield of EUS compared with WLE/BX for evaluation of residual disease appears limited, especially in patients with benign disease.

Transanal endoscopic surgery with total wall excision is required with rectal adenomas due to the high frequency of adenocarcinoma

BACKGROUND

Colorectal adenomatous polyps are considered premalignant lesions, although a high percentage are already malignant at the time of their removal. Full-thickness excision in patients with adenoma detected in preoperative biopsy enables much more accurate pathology examination and has shown that local surgery is appropriate for T1 adenocarcinoma.

OBJECTIVE

To determine whether full-thickness excision during transanal endoscopic surgery is the treatment of choice for rectal adenoma, and to identify possible predictors of invasive adenocarcinoma associated with this type of lesion.

DESIGN

Prospective, observational study.

SETTING

The study was conducted at a university teaching hospital.

PATIENTS

All patients scheduled for transanal endoscopic surgery after detection of adenoma in a preoperative biopsy between June 2004 and February 2013 entered the study.

MAIN OUTCOME MEASURES

The principal variable was the presence of invasive adenocarcinoma in the pathology study. Other study variables were the epidemiological variables sex and age; the clinical variables tumor size, number of quadrants affected, distance from the anal verge, and tumor location; and the morphological variables tumor aspect, degree of dysplasia, preoperative biopsy (tubulo-villous), endorectal ultrasound, and pelvic MRI stage. Variables found to be related to the risk of malignancy in rectal adenomas were evaluated using univariate and multivariate analysis.

RESULTS

Of 471 patients who underwent surgery, 277 had a preoperative diagnosis of adenoma. Final pathology studies showed 52 (18.8%) invasive adenocarcinomas, among which 27 were pT1 (52%), 16 pT2 (30.7%), and 9 pT3 (17.3%). Factors predictive of invasive adenocarcinoma were sessile morphology (OR 3.2, 95%CI 1.4-7.1), high-grade dysplasia (OR 2.3, 95%CI 1.2-4.8), and endorectal ultrasound stage uT2-T3 (OR 3.8, 95%CI 1.6-9).

LIMITATIONS

The limitations are derived from the observational design.

CONCLUSIONS

In this sample, half of the adenocarcinomas from adenomas were T1 adenocarcinomas. Because a high proportion of rectal adenomas are, in fact, invasive adenocarcinomas, full-thickness excision is appropriate.

High-frequency mini-probe ultrasound as a useful adjunct in the management of patients with malignant colorectal polyps

AIM

Colorectal polyps with a focus of malignancy, identified postpolypectomy, pose a management challenge of whether endoscopic treatment is adequate or whether further surgical resection is required. This study assessed 12- and 20-MHz colonoscopic ultrasound to evaluate the presence of residual disease and local lymph nodes.

METHOD

Consecutive cases of all colorectal polyps with a focus of malignancy were included. Colonoscopic high-frequency ultrasound was performed (20-MHz mini-probes for residual polyps and 12-MHz ultrasound for local lymph nodes) in the region of previous polypectomy. Biopsies were taken of the polypectomy site if any abnormalities were seen.

RESULTS

Twenty-one malignant polyps (sigmoid, n = 10; rectum, n = 8; transverse colon, n = 1; ascending colon, n = 1; and caecum, n = 1) were identified. All were invasive adenocarcinomas; 12 were intramucosal and nine were submucosal (seven sm1 lesions in the upper third of the submucosa; and two sm2 lesions in the middle third of the submucosa). Excision was histologically complete in 12 patients, four had involved margins and histology was uncertain in five owing to diathermy artefacts. Further colonoscopy revealed a residual abnormality in eight patients. The 12- and 20-MHz ultrasound imaging revealed mucosal irregularity with normal bowel-wall layers and no lymph-node involvement, with normal histology. High-frequency ultrasound was normal in the remaining 13 patients. At the time of writing, 15 (72%) of the 21 patients were disease free without further surgery. Six of the 21 patients underwent surgery, despite normal high-frequency ultrasound findings, because of submucosal invasion (sm1 or sm2) and uncertain completeness of resection. The specimens were free of cancer in all six patients.

CONCLUSION

High-frequency ultrasound is feasible for the assessment of colorectal malignant polyps.

How useful is rectal endosonography in the staging of rectal cancer?

It is essential in treating rectal cancer to have adequate preoperative imaging, as accurate staging can influence the management strategy, type of resection, and candidacy for neoadjuvant therapy. In the last twenty years, endorectal ultrasound (ERUS) has become the primary method for locoregional staging of rectal cancer. ERUS is the most accurate modality for assessing local depth of invasion of rectal carcinoma into the rectal wall layers (T stage). Lower accuracy for T2 tumors is commonly reported, which could lead to sonographic overstaging of T3 tumors following preoperative therapy. Unfortunately, ERUS is not as good for predicting nodal metastases as it is for tumor depth, which could be related to the unclear definition of nodal metastases. The use of multiple criteria might improve accuracy. Failure to evaluate nodal status could lead to inadequate surgical resection. ERUS can accurately distinguish early cancers from advanced ones, with a high detection rate of residual carcinoma in the rectal wall. ERUS is also useful for detection of local recurrence at the anastomosis site, which might require fine-needle aspiration of the tissue. Overstaging is more frequent than understaging, mostly due to inflammatory changes. Limitations of ERUS are operator and experience dependency, limited tolerance of patients, and limited range of depth of the transducer. The ERUS technique requires a learning curve for orientation and identification of images and planes. With sufficient time and effort, quality and accuracy of the ERUS procedure could be improved.

Endosonographic staging of lower intestinal malignancy

The use of EUS in the assessment of rectal pathology is well established. The accurate staging of lower intestinal tumours predicts prognosis and guides the planning of individual patient treatment. Increased experience and the development of high resolution three-dimensional EUS has lead to the greater accuracy of rectal staging with EUS of rectal tumours now considered the gold standard showing T stage accuracy that ranges from 75% to 95%, with N stage accuracy ranging from 65% to 80%. The use of EUS in the staging of colonic pathology, however, is not so well established though advances in miniprobe EUS has improved the assessment of colonic tumours. EUS is also of benefit in the assessment of anal pathology though here, accurate correlation with histology has not been firmly established.

Full thickness transanal re-excision following endoscopic removal of malignant rectal polyps

PURPOSE

Segmental resection is recommended for malignant polyps of the colon that are removed endoscopically with questionable margins. However, when such a lesion is present in the rectum, radical resection may involve a higher risk procedure such as low anterior resection or abdominoperineal resection. We report our long-term results in patients treated by transanal re-excision (TAR) following endoscopic removal of malignant rectal polyps (MRP).

METHODS

Twenty-three patients were identified between 2000 and 2006 as having undergone TAR following complete gross endoscopic removal of an MRP. All lesions demonstrated close, unclear, or microscopically positive polypectomy margins.

RESULTS

Our population consisted of 13 men and 10 women with a median age of 61 years (range 52-86). Seventeen (74%) patients demonstrated no evidence of residual tumor. Six patients were found to have residual disease (three adenoma, two adenocarcinoma, one positive lymph node). Morbidity was minimal, and there were no mortalities. At a median follow-up of 64.6 months (range 11-90), there have been no recurrences.

CONCLUSION

We conclude that in approximately one quarter of patients, residual disease is identified following TAR. Given the relatively safety and the low recurrence rate associated with this procedure, TAR may be considered as an alternative to radical resection for MRPs with unsatisfactory margins.

An update on imaging of colorectal cancer

Screening of asymptomatic average-risk patients for presence of colon cancer and early detection in precursor stages is of great interest to general population. Comprehensive evaluation of symptomatic or high-risk patients represents another important clinical focus. Available techniques for total colon imaging, rectal cancer staging and the role of positron emission tomography are discussed.

Evaluation of benign and malignant rectal lesions with CT colonography and endoscopic correlation

Colorectal carcinoma is a significant cause of death from cancer in the United States, and early detection and treatment are critical. Computed tomographic (CT) colonography is a noninvasive, rapidly evolving technique that is a potential alternative to conventional colonoscopy for colorectal cancer screening. Rectal disease (eg, polyps, cancerous lesions, extramucosal lesions, inflammatory disease) can be especially challenging to diagnose with CT colonography because of several factors that can simulate or obscure the disease (eg, over- or underdistention, rectal tube, stool, artifacts). Familiarity with the spectrum of rectal diseases and with the potential pitfalls and technical limitations of CT colonography will help minimize interpretative and perceptual errors.