Douglas K. Rex, MD Indiana University Hospital Indianapolis, IN

Transcription

1 Serrated Adenomas: What do they mean and what to do about them? Douglas K. Rex, MD Indiana University Hospital Indianapolis, IN Colorectal Cancer Molecular Basis Pathway Frequency Genes MSI Precursor Speed CIN 65-70% APC K-ras p53 No Adenoma Slow Lynch 3% MLH1 Yes Adenoma Fast MLH2 MLH6 PMS2 CIMP 30-35% BRAF Sometimes Serrated Can be fast 1

2 Residual risk after colonoscopy: right vs left colon Brenner 2011 Singh, G 2007 Singh, H 2010 Left-sided Right-sided Baxter, What is the significance of the serrated pathway? Features of interval cancers Proximal location MSI positive CIMP positive 2

3 Minimal Terminology of Serrated Lesions (WHO) Hyperplastic polyp (HP) Sessile serrated adenoma/polyp (SSA/P) With cytological dysplasia Without cytological dysplasia Traditional serrated adenoma (TSA) Therefore The WHO recommends that the term serrated adenoma always be preceded by a qualifier: Sessile serrated adenoma/polyp (SSA/P) Traditional serrated adenoma (TSA) 3

4 Features of major categories of serrated lesions WHO classification Prevalence Shape Distribution Malignant potential Hyperplastic polyp Very common Sessile/flat Mostly distal Very low Sessile serrated adenoma/ polyp Traditional serrated adenoma Common Sessile/flat 80% proximal Significant Rare Sessile/ pedunculated Mostly distal Significant 2416 SSA/Ps SSA/P SSA/P with LGD SSA/P with HGD mean age 61y 66y 72y SSA/P with cancer 76y Lash, J Clin Pathol 2010;63:

5 The serrated pathway Hyperplastic polyp?? Sessile serrated adenoma/polyp probably slow SSA/P with cytologic dysplasia sometimes fast CIMP colon cancer So. SSA/P is the main precursor of CIMP-high CRC No reliable way to distinguish HP from SSA/P endoscopically Agreement for pathologists distinguishing HP from SSA/P is moderate Most large serrated lesions in the proximal colon are SSA/P SSA/P with cytological dysplasia is a dangerous lesion 5

6 Clinical associations of serrated polyps with CIMP-high CRCs SSA/P histology (vs hyperplastic) Proximal location (vs distal) of serrated lesions Size (big vs small) of serrated lesions Number (more vs fewer) of serrated lesions Variable detection of proximal colon serrated lesions among GI docs Number of doctors Lowest proximal colon serrated lesion detection rate Highest proximal colon serrated lesion detection rate Range Hetzel Boston % 7.6% 6.9 Kahi Indiana 15 1% 18% 18 6

7 Variable detection of adenomas among GI docs Number of doctors Lowest ADR Highest ADR Range Barclay Illinois 2006 Chen Indiana 2007 Imperiale Indiana 2009 Shaukat Minnesota % 32.7% % 41.1% % 44% % 39% 3.9 Endoscopic features of serrated lesions in the proximal colon mucus cap normal vascular pattern obscured pale color indistinct edges few blood vessels on the surface deformable during snaring 7

8 Serrated polyps hot snare resection Serrated lesions 8

9 How do you know if you re a good serrated lesion detector? Measure your adenoma detection rate ADR correlates well with proximal colon serrated lesion detection Serrated lesion detection rate is going to be problematic Poor agreement on SSA/P vs HP Deciding on what s the proximal colon WHO definitions of serrated polyposis (formerly hyperplastic polyposis) 20 or more serrated polyps throughout the colon Serrated polyp in FDR with serrated polyposis 5 serrated polyps proximal to the sigmoid of which 2 are 10 mm in size 9

10 Serrated polyposis Recommendations for surveillance Interval HP rectosigmoid only; any number 10 HPs 5mminsize size, 3 in number proximal to the sigmoid 10 4 serrated polyps proximal to sigmoid, any size 5 Any serrated polyp > 5 mm in size proximal to sigmoid 5 SSA/P or TSA 5 SSA/P or TSA 10 mm 3 SSA/P with dysplasia serrated polyps 10 mm in size proximal to sigmoid (consider serrated polyposis) 1-3 Serrated polyposis 1 10

11 Serrated lesions: conclusions SSA/P and TSA are pre-malignant lesions SSA/P and HPs have a distinct endoscopic appearance; measure your ADR Most large proximal colon serrated lesions are SSA/Ps Remove all the serrated lesions proximal to the sigmoid and all those > 5 mm in distal colon Follow-up is closer for SSA/P or TSA, large size, increased numbers of proximal lesions 11

12 Serrated polyps RR of CRC after colonoscopy in Ontario 12

13 Residual right colon protection Singh H, et al Gastro 2010;139: Singh,H Negative colonoscopy by GI GI Non-GI Right colon cancers after colonoscopy Baxter, et al Gastro 2011;140:65-72 RR interval proximal cancer Other Surgeons GI docs

14 Polypectomy rates (relative to rates 10%) Residual right colon cancer Residual right colon cancer 25-29% >=30% Residual right colon cancer Serrated colorectal polyps 14

15 Coexistence of serrated lesions and adenomas Serrated polyposis 15

16 Resection methods injection and snaring Resection methods 16

17 Managing FDRs of patients with serrated polyposis No genetic testing is available Colonoscopy every 5 years beginning 10 years the age at diagnosis of the proband (or as dictated by the polyp findings) 17