Role of colonoscopy in the treatment of malignant polyps Pathology of malignant colorectal polyps Assessing the risk of residual disease post-polypectomy Surgical salvage of the high-risk polyp Staging & non-endoscopic surveillance of malignant polyp

Endoscopist BEFORE Histopathologist Predict polyp histology by morphology – OPTICAL Bx Aim for en bloc resection – AVOID piece-meal

Endoscopist BEFORE Histopathologist Endoscopy reporting Site – Right Vs left colon (splenic flexure) Size – >35mm – 75% of carcinoma Pedunculated / Sessile - Villous 15% risk of Ca Morphology – irregular, ulcer, hard, broad stalk Paris classification of appearance Kudo classification of pit pattern Laterally spreading lesion Non-lifting sign One-piece / PiecemealCompleteness of excision Benign / Malignant

Histopathologist Malignant Colorectal Polyp is a lesion in which neoplastic cells have invaded through the muscularis mucosae into the submucosa. pT1 adenocarcinoma is defined as invasion into the submucosa but not into the muscularis propria Carcinoma in situ / intramucosal carcinoma - OBSOLETE (High Grade Dysplasia)

Histopathologist Degree of differentiation Size – microscopic assessment is most accurate Level of invasion into polyp – Haggitt & Kikuchi

Histopathologist Depth of invasion into submucosa HaggittKikuchi

Histopathologist Degree of differentiation Size – microscopic assessment is most accurate Level of invasion into polyp – Haggitt & Kikuchi Resection margin ≤ 1mm is an involved margin LVI, tumour budding, cribriform histology

Histopathologist 2 nd opinion due to interobserver variability Degree of differentiation LVI

Estimation of risk of residual disease Malignant polyp – Colorectal MDT Estimate the risk of residual disease Technique of resection Resection margin Degree of differentiation Depth of invasion – Haggitt and Kikuchi LVI

Estimation of risk of residual disease Surgery should be considered, provided that the patient is fit enough to undergo such surgery where resection margin is deemed to be involved (< 1 mm) Haggitt Level 4 or Kikuchi sm3 Kikuchi sm1 or sm2 with adverse histology Poorly differentiated – is unusual Colon Vs Rectum differences

Estimation of risk of residual disease Surgery should be considered, provided that the patient is fit enough to undergo such surgery where resection margin is deemed to be involved (< 1 mm) Haggitt Level 4 or Kikuchi sm3 Kikuchi sm1 or sm2 with adverse histology Poorly differentiated – is unusual Lymphovascular invasion Tumour budding Cribriform Mucinous In isolation NOT High risk

Estimation of risk of residual disease

Surgical decision making in high-risk polyps Fitness Life expectancy Impact of morbidity Mortality Patient wishes Surgery if predicted op mortality (CR-POSSUM) < risk of residual disease It should be remembered that even in ‘high-risk polyps’, it is more likely that the resected specimen will NOT contain any evidence of residual disease at the polypectomy site or in draining lymph nodes.

Staging and surveillance - TNM T – Little data on use of MRI or EUS for residual disease N – MRI or EUS unreliable (Not accurate enough to judge whether a visible lymph node does NOT contain cancer) M – CTCAP

Staging and surveillance - TNM Endorectal US should be performed on all rectal polyp tumours prior to transanal or surgical excision (good practice BUT no good evidence)