Mrs BP• 67yo woman – referred for screening colonoscopy for
+ve FOB• Index colonoscopy in Sep 2009– Multiple polyps; largest was resected (TVA)
– Rebooked 8mo later for resection of remaining smaller polyps
Mrs BP – Colonoscopy 6mo later
• Caecal ulcer– Failed to lift with submucosal injection of saline– Biopsied -> Carcinoma in situ
Mrs BP - Surgery
• Proceeded to R hemicolectomy– Early T2 CRC -> just infiltrating muscularis propria– Loss of nuclear staining seen for MLH1 and PMS2
(consistent with microsatellite instability)– 0/10 lymph nodes involved– No adjuvant chemo recommended
• Tumour was surrounded by flat lesions which were sessile serrated adenomas (SSA)
Colonoscopy in screening for CRC
• Screening colonoscopy in 1994 asymptomatic adults– 5.7% had advanced neoplasms
Lieberman DA, et al N Engl J Med. 2000;343(3):162
• Asymptomatic individuals (mean age 61) colonoscoped then followed for 8 years have reduced CRC incidence and death compared to expected incidence and SEERS data
Kahi CJ, et al. Clin Gas Hepat. 2009;7(7):770
Expected Adenoma Detection Rate
• Overall, in 10034 colonoscopies, 29.1% had at least 1 adenoma removed.
• Males vs Females (24.5% vs 16.7%; p<0.0001)Chen & Rex J Clin Gastro 2008; 42(6): 704-707
Age 30 50 70
> 1 adenoma or cancer
14.6% (13.2-16) 23.3%(20.1-26.9) 35.2%(29.5-41.4)
> 1 nonadenoma/non
cancer
26%(24-28.1) 27.6%(24.3-31.3) 29.3%(24.5-34.6)
⏎
Risks of Colonoscopy
• 1 in 1000 of perforation or major bleeding• 0.8/1000 if no biopsy• 7/1000 if polypectomy or biopsy
Polyp detection depends on endoscopist
• Risk of interval cancer between screening colonoscopy and repeat procedure depends on endoscopist’s adenoma detection rate
• Withdrawal time of 6 minutes or more increases adenoma detection rate
Barclay RL, et al. N Engl J Med. 2006;355(24):2533
Less effective in R sided lesions?
• Colonoscopy reduces deaths mainly from L sided CRC, but not R sided lesions:
Baxter NN, Ann Intern Med. 2009;150(1):1.Singh H, Gastroenterology. 2010;139(4):1128
• 5% of CRCs arise as “interval” cancers following a colonoscopy
Sessile Serrated Adenomas
• Distal polyps usually follow conventional adenoma-carcinoma sequence
• Up to 20% of all CRCs may arise from serrated polyps
• Only recognised as recently as 2003• Serrated pathway polyps become cancers with
high levels of microsatellite instability (MSI)• Can become cancers more rapidly than
conventional adenomas
Sessile Serrated Adenomas (2)
• SSAs represent 1-9% of all polyps• Present in 1-4% of the general population• Median age of patients 61• Trend toward female gender bias• More commonly in the proximal colon• Endoscopic appearance:
– 5mm or larger– Flat or depressed– Covered by adherent layer of yellowish mucus
• In patients with at least one SSA– 12% have LGD; 2% have HGD; 1% have adenocarcinoma
Huang CS, et al. Am J Gastro 2011; 106: 229-240⏎
Natural History of SSAs
• Lu F, et al. Am J of Surg Path 2010; 34(7):927-934– All colonic polyps dx between 1980-2001 studied– 1402 hyperplastic polyps– 81 polyps in 55 pts rediagnosed as SSA– 40 SSA pts with no prev hx of CRC or AP-HGD
• Of these, 5 developed CRC, 1 developed AP-HGD• CRC more commong in SSA pts than in controls with HP (12.5% vs
1.8%) and AP (12.5% vs 1.8%)• All subsequent CRC or AP-HGD developed in proximal colon• 4 of 5 subsequent CRC showed MSI
• Conclusion: 15% of SSA pts developed subsequent CRC or AP-HGD; especially in the R colon
Risk factors for developing SSAs
• Cigarette smoking• Obesity• Female gender• Family history of CRC or polyps
How quickly to SSAs progress to cancer
• We don’t know• Case study suggesting SSA-> CA in 8 months• Mrs BP
Surveillance post-resection
• SSA with no dysplasia– 5 years if <3 lesions, all <1cm in size– 3 years if 3 or more, or any 1cm or more in size
• SSA with dysplasia– 3 years
• Screening of first-degree relatives at age 40, or 10y prior to age of diagnosis
We are missing SSAs!
• Mortality rates from R sided CRC not decreasing despite increasing use of screening colonoscopy
• Interval cancers more likely to occur in proximal colon and demonstrate microsatellite instability suggesting they arise from SSAs
• Adherent mucus coating is not a useful endoscopic sign unless prep is very good
Recognising SSAs
• Colonoscopy is the only reliable technique• Increasing recognition of SSA • 6 min withdrawal time• Split dose bowel preparation• Advanced imaging techniques– Narrow Band Imaging– Indigo Carmine spray
Split dose Colonic Preparation
• Traditional colonic preparation consists of solution given day prior to colonoscopy
• Split dose prep involves giving for example, 2L of prep the day prior, and 1L on the morning of colonoscopy
Clear superiority of Split Dose Prep
• Achieves better cleansing than conventional– Good/excellent views 75% vs 43% (p=.00001)– Best views within 8 hours of last fluid intake
• Adenoma detection rates higher– 24% vs 12%, (p=0.001)
• Lower rates of failed caecal intubation– 1% vs 11%; (p=0.00001)
• Fewer aborted procedures– 7% vs 21%, (p<0.0001)
Marmo R, et al. Gastrintest Endosc. 2010 Aug; 72(2):313-20.
Patient acceptance of split-dose bowel prep
• In comparisons bet split dose and conventional:– Higher patient satisfaction scores– Higher “no or minimal difficulty” completing– No significant difference in percentage of patients who
stop for a bowel movement on way to proc– No difference in compliance
Khan, MA, et al. J Clin Gast. 2010; 44(4):310-1 (Letter)
Park, JS, etal. Endoscopy. 2007; 39(7):616-9
• Majority of patients willing to get up early to take split dose Rex DK, et al. Dig Dis Sci. 2010; 55(7): 2030-4
Anaesthetic concerns re morning prep
• Traditionally patients have fasted overnight for colonoscopy
• Some anaesthetists argue that aspiration risk higher if morning prep is taken
• But residual gastric fluid volume similar between split-dose regimen vs conventional
Huffman M, Gastrointest Endosc. 2010 Sep; 72(3): 516-22
• Anaesthetic guidelines have reduced precolonoscopy fasting to 2 hours.
Image Enhanced Colonoscopy
• Includes:– Endoscope based image enhancing:• NBI (Olympus)• iScan(Pentax)
– Chromoendoscopy• Indigo carmine dye
NBI/FICE/iScan
• iScan (Pentax) increases detection of neoplasia over white light (38% vs 13%)
• FICE (Fuji) showed no difference in adenoma detection over white light
• NBI (Olympus) increases detection of flat adenomas over white light, but not adenomas overall.
• FICE (Pentax) vs Indigocarmine – no difference in adenoma detection rates
Hoffman A. et al. Endoscopy. 2010 42(10):827-33Chung SJ, et al. Gastrointestinal Endoscopy. 2010; 72(1):136-42
Paggi S, et al. Clin Gas & Hep. 2009; 7(10) 1049-54Pohl J, et al. Gut. 2009; 58(1):73-8
Chromoendoscopy
• Spraying of indigo carmine through the flushing channel of the colonoscope
• Increases detection of flat lesions and hyperplastic polyps, but not of adenomas overall. Le Rhun M, et al. Clin Gas & Hep. 2006; 4(3):349-54
What makes a colonoscopy a (good) colonoscopy?
• SPLIT DOSE COLONIC PREP• At least 6 minutes withdrawal• +/- image enhancing in the R colon (NBI or
indigo carmine)• Endoscopist consciously looking for flat R
sided lesions
Endoscopist Report Card• Ultimately all endoscopists should audit their
adenoma detection rate• My performance in 81 colonoscopies between
Mar and May 2013 at 1 facility:Successful caecal intubation 100%
Split Prep 100%
Prep “good or satisfactory” 93%
Complications 0%
Adenoma Detection Rate(incl SSA)
45.6%
SSA percentage of all polyps 18.9%
SSA detection rate 8.7%
Top Related