Colorectal Adenomas

Santhat Nivatvongs MD

Mayo Clinic

Rochester Minnesota

U. S.A.

ADENOMATOUS POLYPS OF COLON AND RECTUM

• Incidence

• Risk factors of an adenoma

• Natural history of an adenoma

• Serrated adenoma

• Colonoscopic polypectomy

AUTOPSY SURVEY658 Adenomas

Distribution (%)

Rectum 7 Other Findings

Sigmoid 17 Ave size 0.6 cm

Descending 9 Mean # 2.6

Transverse 28 increase # with age

Ascending 26 No increase in size with age

Cecum 13 11 invasive Ca ( 1.7 % )

Rickert et al Cancer 1979;43:1847

COLONOSCOPIC INITIAL EXAM

%

Adenoma 85

Hyperplastic 15

Total 100

National Polyp Study Gastroent 1990; 98:371

Size of Colorectal AdenomaInitial Colonoscopy

Size ( cm ) %

< 0.5 38

0.6-1.0 37

> 1.0 25

Total 100

National Polyp Study Gastroent 1990; 98:371

Colorectal AdenomaIndependent Risk Factors For High Grade Dysplasia

• Size

• Extent of Villous

• Increasing age National Polyp study Gastroent 1990;98:371

Size of Adenoma And Invasive Ca

Size (cm) Invasive Ca (%)

< 0.5 0

0.6-1.5 2

1.6-2.5 19

2.6-3.5 43

> 3.5 76

Nusko G et al. Endoscopy 1997; 20:626

Colorectal Adenoma

Advanced Adenoma

• Adenoma > 1 cm

• Villous component

The Adenoma -Carcinoma Sequence in Cancer of the Colon

Raymond J. Jackman, M.D. and Charles W. Mayo, M.D.,

Rochester, Minnesota

Surg Gynecol Obstet 1951;93:327

Natural History of Small Adenomas

Colorectal Adenomas < 5 mm

30 dimunitive adenomas (26 pt) Follow-up 2 yr

Mean growth 0.6 mm / yr

2 / 30 reached 10 mm

Bersentes K et al. Am J Gastroent 1997 ; 92 : 117

Natural History of Colorectal Adenomas

68 adenomas < 1 cm ( 58 pt ) Follow- up 3 yr

17 ( 25 % ) same size

27 ( 40 % ) grew ---- most rapid = 4mm in 3 yr

24 ( 35% ) shrunk

Hofstad B et al. Gut 1996; 39 : 449

Natural History of An Adenoma1 cm or Larger

N = 226

Mean Follow-up 5 yr (1-27 yr)

%

Disappear 5

No Growth 57

Growth 38 Otchy D et al. Am J Gastro 1996; 91:448

Natural History of An Adenoma

Risk of >1cm adenoma

Year Invasive Ca.(%)

5 2.5

10 8.0

15 24.0 Stryker S et al. Gastroent 1987; 83:1009

Progression of Adenoma and Carcinoma

From clean colon to adenoma 5 yr

From clean colon to carcinoma 10 yr

Winawer SW et al. Cancer 1991; 67:1143

Serrated Adenomatous PolypHistorical Perspectives

Hyperplastic in adenomatous polyp

Goldman H et al. Arch Pathol 1970; 89 : 349

Mixed hyperplastic adenomatous polyp Urbanski SJ et al. Am J Surg Path 1984; 8: 551

Serrated adenoma

Longacre TA, Fenoglio – Preiser CM . Am J Surg Path 1990; 14: 524

Molecular Study of Serrated Adenoma No APC mutation

Kras mutation

DNA microsatellite instability ( MSI – L )

Loss of Chromosome 1 P

Mutation of TGF beta RI I

Genetic = neoplastic polyp

Jass JR DCR 2001; 44: 163

Risk Features of Serrated Adenoma

Size > 1 cm

Location in right colon

Presence of high grade dysplasia

Coincidental adenoma

1 st degree relatives with HGD

1 st degree relatives with CR Ca Jass JR DCR 2001 ; 44 : 163

Colonoscopic Polypectomy

Size of Polyps

Size No. %

0.5 - 0.9 674 26

1.0 - 1.9 1296 50

2.0 – 2.9 311 12

3.0 – 3.9 78 3

4.0 – 6.0 52 2

Unretrieved 181 7

Total 2592 100

Colonoscopic PolypectomyComplications in 2592 Polyps

Problem No.

Bleeding 20 ( resulted in 1 death )

Transmural burn 8 ( conservative treatment )

Perforation 2 ( conservative treatment )

Intra-abdominal abscess 1 ( CT drain )

Snare entrapment 1 ( surgery )

Ensnared bowel wall 1 ( surgery )

Total 33 ( 1.3% )

ADENOMATOUS POLYPS OF COLON AND RECTUM

• Incidence

• Risk factors of an adenoma

• Natural history of an adenoma

• Serrated adenoma

• Colonoscopic polypectomy