Endoscopic mesorectal dissection for precise pathologic staging and potential treatment of locally advanced rectal cancer

Abstract

Background and Aims

Traditional surgical techniques for rectal cancer resection may face limitations in accessing lesions at extreme rectal locations. Endoscopic mesorectal dissection (EMD) enables wide-margin resection without the constraints of conventional surgery. We present a case demonstrating the feasibility of EMD for accurate, organ-sparing staging of rectal cancer. A 67-year-old man with abdominal pain and positive Cologuard test (Exact Sciences Corporation, Madison, Wis, USA) results underwent colonoscopy that revealed a 2-cm sessile polyp 12 cm from the anal verge, removed with a hot snare. Pathology showed invasive adenocarcinoma with positive deep margins. Given challenges with low anterior resection and transanal total mesorectal excision, EMD was selected for precise staging.

Methods

Endoscopy revealed a 15-mm postpolypectomy scar with nodularity. Lesion borders were marked, and methylene blue injection achieved partial lift. A circumferential incision exposed the muscularis propria, allowing full-thickness myotomy into the perirectal fat. The 35-mm lesion was dissected and retrieved en bloc, and the defect was closed with OverStitch sutures (Boston Scientific Corporation, Marlborough, Mass, USA).

Results

Pathology confirmed pT2 adenocarcinoma with R0 margins. The patient had no adverse events, demonstrating the technical success of EMD in achieving en bloc R0 resection.

Conclusions

EMD achieved en bloc R0 resection, highlighting its efficacy as a minimally invasive, organ-sparing approach for precise staging of rectal cancer.

Introduction

Surgical techniques for resection of rectal cancer like low anterior resection (LAR) can carry significant morbidity and mortality. For certain early-stage rectal cancers (<3-4 cm in size), local excision techniques like transanal endoscopic microsurgery (TEM) and transanal minimally invasive surgery (TAMIS) can achieve wide R0 margins by removing with wide-field full-thickness excision but can sometimes face difficulty in accessing lesions at the most proximal, anterior, and distal parts of the rectum.^1,2 Endoscopic full-thickness resection devices using over-the-scope devices allow for more colorectal access but can be limited by the size of the lesion.³ Endoscopic mesorectal dissection (EMD) allows endoscopists to remove lesions of a variety of sizes in the rectum and play a role in staging of rectal cancers.⁴ Based on data extrapolated from endoscopic submucosal dissection literature, EMD may offer several advantages, including lower adverse event rates, shorter procedure times, reduced hospital stays, and less morbidity when compared to TAMIS and TEM, while still achieving comparable R0 resection rates. Additionally, EMD can access lesions in challenging locations such as the upper rectum (typically 10-12 cm above the anal verge), lesions along the anterior wall, or in patients with a narrow pelvis.5, 6, 7 In Video 1 (available online at www.videogie.org), we present a case of EMD for pathologic staging of a rectal tumor, highlighting its ability to achieve precise, R0 margin resection with a high degree of safety, organ preservation, and therapeutic potential in locally advanced rectal cancer (Fig. 1).

Figure 1.

Full-thickness defect following endoscopic mesorectal dissection of the rectal cancer lesion, demonstrating complete excision of the lesion with exposure of the perirectal fat.

Case description

A 67-year-old man with hyperlipidemia presented after a positive multitarget stool DNA test (Cologuard, Exact Sciences Corporation, Madison, Wis, USA) and 6 months of intermittent lower abdominal pain. Subsequent colonoscopy revealed a 2-cm sessile polyp at the second valve, 12 cm from the anal verge, with central depression and nodularity indicating submucosal invasion and concern for adenocarcinoma. The polyp was removed with hot snare and the polypectomy site tattooed. Pathology showed invasive adenocarcinoma, with a positive vertical margin. Therefore, residual malignancy could not be ruled out. Abdominal and pelvic CT and magnetic resonance imaging were done to further evaluate the site. They did not show lymphadenopathy but were not able to provide information on depth of invasion.

The patient was discussed at a multidisciplinary tumor board, and local excision was recommended for staging. During an attempt at transanal excision, the standard of care in such lesions, the lesion was observed to be in a proximal location behind a fold, making local excision challenging. LAR and total mesorectal excision were also considered; however, these approaches carry undue higher morbidity risk and were thought to be overly invasive in this patient. Endoscopic approach with endoscopic full-thickness resection offered a less-invasive alternative, but given the prior difficulties with snare slippage following clip deployment, particularly in angled lesions, the team favored EMD for diagnostic and potentially therapeutic purposes.

Colonoscopy was performed. A 15-mm postpolypectomy scar was found in the rectum (Fig. 2). Adjacent mucosal findings included discoloration and nodularity. Preparations were made for endoscopic mesorectal dissection (Video 1). The borders of the lesion were marked with the needle tip. We injected 20 mL of methylene blue in the submucosal space with partial lift of the lesion from the muscularis propria. A circumferential incision around the lesion into the submucosa was performed with an endoscopic submucosal dissection knife (DualKnife J; Olympus Corporation, Tokyo, Japan), exposing the muscularis propria.

Figure 2.

Postpolypectomy scar with residual India ink tattoo marking the previous resection site. Pathology from the initial polypectomy revealed positive margins, indicating incomplete excision.

To achieve en bloc resection of the lesion, full-thickness myotomy was performed to expose the perirectal fat. Circumferential full-thickness dissection was completed using an electrosurgical generator and dissection instrument (VIO 3 preciseSECT; Erbe Elektromedizin GmbH, Tübingen, Germany), allowing for controlled cutting and coagulation. The lesion was dissected from the perirectal fat with the electrocautery knife and retrieved with a Roth net (Steris Healthcare, Mentor, Ohio, USA). The resection bed revealed mesorectum and perirectal fat without high-risk vasculature. A 35-mm area was resected (Fig. 3). There was no bleeding at the end of the procedure (Fig. 1). Sutures were placed to close the open defect after full-thickness resection. Using an endoscopic suturing system (OverStitch; Boston Scientific Corporation, Marlborough, Mass, USA), we placed 2 sutures in a running fashion with cinches on both ends with good tissue approximation (Fig. 4). The procedure lasted 40 minutes. The patient was provided with a single dose of ciprofloxacin 400 mg intravenously as prophylaxis. The patient was discharged the same day, with no immediate adverse events reported apart from mild tenesmus, which resolved shortly after the procedure. On 3-month follow-up, the patient reported no new symptoms.

Figure 3.

Closure of the full-thickness defect using the OverStitch 2.0 device (Boston Scientific Corporation, Marlborough, Mass, USA), with sutures secured by a cinch, ensuring defect approximation and tissue apposition.

Figure 4.

Gross specimen of a 35-mm resected tissue fragment following wide excision, demonstrating clear margins surrounding the lesion.

Pathology was notable for an invasive moderately differentiated adenocarcinoma of 8 mm. Carcinoma invaded focally into muscularis propria without further extension. Lymphovascular invasion was also identified with intermediate tumor budding. The margins were R0. American Joint Committee on Cancer staging was determined to be pT2 (Figure 5, Figure 6, Figure 7). Given pathology finding, the patient was again discussed by a multidisciplinary tumor board, and a decision was made to offer LAR with subsequent adjuvant oxaliplatin and capecitabine chemotherapy. Pathology from LAR showed no residual tumor. Sixteen lymph nodes were obtained; 1 was notable for metastatic adenocarcinoma.

Figure 5.

Histopathologic image (hematoxylin and eosin stain, original magnification ×20) showing an 8-mm moderately differentiated adenocarcinoma with invasion into the muscularis propria (arrows) and lymphovascular invasion. Resection margins were negative, and the tumor was staged as pT2, according to American Joint Committee on Cancer criteria.

Figure 6.

Histopathologic image (hematoxylin and eosin stain, original magnification ×40) showing invasive carcinoma (arrows) involving the muscularis propria. The adjacent resection margin, inked blue at the bottom of the image, is negative for tumor involvement.

Figure 7.

Histopathologic image (hematoxylin and eosin stain, original magnification ×100) showing moderately differentiated adenocarcinoma with moderate nuclear pleomorphism, luminal necrosis (arrows), and a cribriform glandular pattern.

Discussion

In this video, we demonstrate the use of EMD to resect a residual cancerous lesion that could not be completely removed with hot snare polypectomy. EMD can be an alternative to local surgical excision in difficult locations. Based on data extrapolated from endoscopic submucosal dissection literature, EMD may offer several advantages, including lower adverse event rates, shorter procedure times, reduced hospital stays, and less morbidity compared with TAMIS and TEM, while still achieving comparable R0 resection rates. Additionally, EMD can access lesions in challenging locations such as the upper rectum (typically 10-12 cm above the anal verge), lesions along the anterior wall, or in patients with a narrow pelvis.5, 6, 7 In this case, EMD achieved an en bloc, R0 resection, with histologic confirmation of invasion into the muscularis propria. The presence of the mesorectum facilitated a contained full-thickness resection, and the defect was successfully closed using the OverStitch device. The wide-field exposure afforded by EMD enabled clear delineation between the tumor and surrounding fibrosis, allowing en bloc resection.

Importantly, this case highlights EMD's utility not only for accurate staging but also for curative resection of postpolypectomy residual tumors, allowing for organ preservation. Total mesorectal excision remains the standard treatment for T2 rectal cancers because of a 12% to 28% risk of lymph node metastases.⁸ However, local endoscopic resection may be appropriate in carefully selected patients as part of a multidisciplinary treatment strategy. Furthermore, as data evolve on blood-based tumor markers and adjuvant chemotherapy or radiation, more patients may be able to avoid invasive surgery in favor of close endoscopic surveillance. This case highlights the potential of rectal EMD as a curative, organ-preserving alternative to surgery in select patients, offering accurate staging and en bloc R0 resection of postpolypectomy residual tumors through a minimally invasive approach.

Patient consent

The patient in this article has given written informed consent to publication of their case details.

Disclosure

All authors disclosed no financial relationships.

Supplementary data

Video 1

Endoscopic mesorectal dissection of a rectal cancer