What are the indications and contraindications for Endoscopic Mucosal Resection (EMR) in patients with colorectal polyps or gastrointestinal cancer?

Endoscopic Mucosal Resection: Indications and Contraindications

Primary Indication

EMR is the preferred treatment for large (≥20 mm) non-pedunculated colorectal lesions, as it provides complete resection while avoiding the higher morbidity, mortality, and cost of surgical alternatives. 1

Specific Indications by Lesion Size

Large Lesions (≥20 mm)

• EMR is strongly recommended as first-line therapy for all non-pedunculated colorectal lesions ≥20 mm in diameter 1
• These procedures must be performed by endoscopists experienced in advanced polypectomy 1
• The technique achieves low severe adverse event rates (1%) and acceptable recurrence rates (14%) based on systematic review of 6,442 patients 1

Medium Lesions (10-19 mm)

• Cold or hot snare polypectomy (with or without submucosal injection) is suggested for 10-19 mm non-pedunculated lesions 1
• However, EMR should be specifically considered for non-polypoid and serrated lesions in this size range, as conventional polypectomy shows 31% incomplete resection rates for these morphologies 1
• Proximal serrated lesions averaging 15.9 mm removed by EMR demonstrate only 3.6% recurrence rates versus much higher rates with conventional techniques 1

Small and Diminutive Lesions

• Cold snare polypectomy is recommended for lesions 5-9 mm 1, 2
• EMR is not indicated for these smaller lesions 1

Indications by Lesion Morphology

High-Risk Morphologic Features Requiring Advanced Technique

• Paris classification 0-IIa+c morphology (elevated with central depression) 3
• Non-granular lateral spreading tumors (LST-NG), particularly with sessile shape or depression 4
• Granular LSTs with dominant nodule 4
• Lesions with Kudo pit pattern type V 3

Standard EMR-Appropriate Morphology

• Paris 0-IIa granular lesions have low submucosal invasion rates (1.4%) and are ideal for EMR 3
• Granular lateral spreading tumors without dominant nodules 4

Specific Clinical Scenarios

When EMR is Preferred Over ESD

• Mucosal or submucosal adenomas >20 mm where piecemeal resection is acceptable (EMR is Grade I recommendation, ESD is Grade II) 4
• Flat lesions 5-20 mm without fibrosis or suspected invasion (EMR is Grade I, ESD is Grade II) 4
• Sessile lesions >10 mm suspected to be villous adenomas or sessile serrated adenomas/polyps (EMR is Grade I, ESD is Grade II) 4

When to Consider ESD Instead of EMR

• Lateral spreading tumors ≥20 mm where en bloc resection is required 4
• Villous adenomas ≥25 mm (ESD is Grade I for these specific lesions) 4
• Lesions suspected to have submucosal invasion 1, 4
• Mucosal lesions with fibrosis 1, 4
• Local residual early carcinoma after prior endoscopic resection 1, 4
• Non-polypoid colorectal dysplasia in inflammatory bowel disease patients 1, 4

Absolute Contraindications

Deep Submucosal Invasion

• NICE 3 classification features (disrupted surface pattern, absent vessels, or dark brown color) predict deep submucosal invasion with 94% accuracy 4
• Kudo pit pattern type VN has 90.4% sensitivity and 88.4% specificity for invasive cancer 4
• JNET Type 3 features (loose vessel areas with interruption of thick vessels, amorphous surface areas) indicate deep submucosal invasive cancer 5
• When these features are present in non-pedunculated lesions, perform limited cold forceps biopsy only in the area of surface disruption, tattoo the site, and refer directly to colorectal surgery 5

Technical Contraindications

• Prior failed EMR attempts are associated with significantly higher risk of incomplete resection or recurrence (OR 3.8) 1, 3
• Ileocecal valve involvement increases risk of EMR failure (OR 3.4) 3

Relative Contraindications and High-Risk Scenarios

Anticoagulation

• Patients on antithrombotics require individualized assessment balancing interruption risks against bleeding risks for lesions ≥20 mm 1

Lesion Location

• Right colon lesions ≥20 mm require prophylactic clip closure of the resection defect to reduce delayed bleeding risk 1, 2

Lesion Size

• Lesions >40 mm have significantly higher recurrence rates (OR 4.37) after EMR 3
• For these very large lesions, consider ESD if en bloc resection is critical 4

Critical Technical Requirements

Resection Technique

• All grossly visible tissue must be resected in a single colonoscopy session and in the safest minimum number of pieces 1
• En bloc resection is preferred when feasible for lesions <20 mm 1
• Piecemeal resection is acceptable for lesions ≥20 mm when performed correctly 1

Injection Solutions

• Viscous injection solutions (hydroxyethyl starch, Eleview, ORISE Gel) are suggested for lesions ≥20 mm to enable fewer pieces and less procedure time 1
• Contrast agents (indigo carmine or methylene blue) should be used to facilitate recognition of tissue layers 1
• Carbon particle suspension (tattoo) must NOT be used as submucosal injection solution, as it causes submucosal fibrosis and reduces future resection success 1

Margin Treatment

• Ablative techniques (APC, snare tip soft coagulation) are contraindicated on endoscopically visible residual tissue, as they increase recurrence risk 1
• Adjuvant thermal ablation of the post-EMR margin is suggested only where no endoscopically visible adenoma remains after meticulous inspection 1, 4, 2

Gastric EMR Indications

Early Gastric Cancer

• EMR is indicated for Tis or T1a tumors (limited to mucosa) 1
• Specific criteria required: well- or moderately differentiated histology, tumors <30 mm, absence of ulceration, no evidence of invasive findings 1
• Node-negative T1 tumors have >90% 5-year survival with limited resection 1
• Routine use outside clinical trials is not recommended and should be limited to medical centers with extensive experience 1

Risk Factors Increasing Lymph Node Metastasis Probability

• Increasing tumor size 1
• Submucosal invasion 1
• Poorly differentiated tumors 1
• Lymphatic and vascular invasion 1

Post-EMR Management

Surveillance Requirements

• Surveillance colonoscopy is mandatory regardless of EMR technique due to risk of residual or recurrent polyp formation 6
• Highest risk patients for recurrence: lesions >40 mm and those treated with argon plasma coagulation 3

Histologic Criteria for Curative Resection

• Submucosal invasion <1 mm 4, 5
• Absence of lymphovascular invasion 4, 5
• Well or moderately differentiated tumor 4, 5
• No tumor budding 4, 5
• Distance of tumor to margin ≥1 mm (negative resection margins) 4, 5
• If any criterion is not met, surgical resection with lymph node dissection is required 5