Colon cancer screening: Updated colonoscopy followup guidelines after polyps detected

 Recent guidelines highlighted some significant differences in follow-up after colonoscopy and polypectomy (see colon ca screening polyp fu jama2020 in dropbox, or doi:10.1001/jama.2020.15001 for a recent summary of recommendations, and colon ca screening low risk adenoma fu gastro2020 in dropbox or doi.org/10.1053/j.gastro.2019.10.026 for the full recommendations from the US Multi-Society Task Force on Colorectal Cancer). The US Multi-Society Task Force included the American College of Gastroenterology, the American Gastroenterological Association, and the American Society for Gastrointestinal Endoscopy 

 

Details: 

-- definitions: 

    -- low-risk adenoma: 1 to 2 nonadvanced adenomas <10mm in size 

        -- advanced adenoma: adenoma at least 10 mm in size, having to tubulovillous/villous histology, or having high grade dysplasia 

    -- high-risk adenoma: advanced neoplasia or 3 or more adenomas 

        -- advanced neoplasia is the same as advanced adenoma above, with the addition of colorectal cancer 

 

-- for patients with 1 to 2 tubular adenomas <10 mm: the new recommendations suggest increasing the screening interval from 5-10 years to 7-10 years 

    -- data suggested that adults with 1 to 2 tubular adenomas <10 mm are at very low absolute risk for metachronous advanced neoplasia at 3 to 5 years follow-up, with the risks comparable to those with normal baseline exams (1.6-3.3%) 

-- those with 5-10 tubular adenomas <10 mm: repeat colonoscopy 3 years after complete removal (5% have metachronous advanced neoplasia vs 1.8% for 3-4 adenomas <10 mm and 1.4% for 1 to 2 adenomas <10 mm)

    -- the data are limited/weak for those with 3 to 4 small adenomas, recommending 3 to 5 years follow-up  

-- new evidence confirms importance for repeat colonoscopy at 3 years for adults with at least one adenoma 10 mm or larger, as well as those with villous histology or high-grade dysplasia 

-- for those with more than 10 adenomas completely removed, repeat colonoscopy at one year (this is a change from the prior recommendation of <3 years) 

-- for those with piecemeal resection of colon polyps at colonoscopy,  repeat colonoscopy in 6 months: increased risk for metachronous or recurrent neoplasia. A meta-analysis found 20% increased risk of local recurrence vs 3% for en-bloc resection of non-pedunculated polyps; 96% of recurrences were detected at 6 months. 

-- For those with sessile serrated polyps 20 mm or larger, recommended follow-up at 6 months. Also, those with sessile serrated polyps should be considered for genetic testing 

Here is summary table:

 

Recommendations for Second Surveillance Stratified by Adenoma Findings at Baseline and First Surveillance (their table 7 in the full article)

Baseline finding	Recommended interval for first surveillance	Finding at first surveillance	Recommended interval for next surveillance
1–2 tubular adenomas <10 mm	7–10 y	Normal colonoscopy	10 y
		1–2 tubular adenomas <10 mm	7–10 y
		3–4 tubular adenomas <10 mm	3–5 y
		Adenoma ≥10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas <10 mm	3 y
3–4 tubular adenomas <10 mm	3–5 y	Normal colonoscopy	10 y
		1–2 tubular adenomas <10 mm	7–10 y
		3–4 tubular adenomas <10 mm	3–5 y
		Adenoma ≥10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas <10 mm	3 y
Adenoma ≥10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high-grade dysplasia; or 5–10 adenomas <10 mm	3 y	Normal colonoscopy	5 y
		1–2 tubular adenomas <10 mm	5 y
		3–4 tubular adenomas <10 mm	3–5 y
		Adenoma ≥10 mm in size; or adenoma with tubulovillous/villous histology; or adenoma with high grade dysplasia; or 5–10 adenomas <10 mm	3 y

Commentary: 

-- it is clear that those with normal colonoscopy have a sustained reduced risk of incident or fatal colorectal cancer (CRC), and this reduced risk in large studies has been found for those receiving another colonoscopy within 3 years (HR 0.35) and after 15 years (HR 0.65). Another huge study (>1.2 million) also confirmed significantly reduced risk after 12 years from a normal colonoscopy. Colonoscopy clearly works. However, this new recommendation continues the 10-year interval after normal colonoscopy screening 

-- these recommendations do emphasize the importance of high-quality colonoscopy: adequate bowel preparation, cecal intubation and photo documentation, complete polyp resection, and colonoscopists who have adequate adenoma detection rate (>30% in men and > 20% in women)

 

-- these recommendations extending the interval for low-risk adenomas were supported by 2 meta-analyses

-- one particularly large recent US study (see colon ca screening low risk adenoma fu gastro2020or doi.org/10.1053/ j.gastro.2019.09.039.): 64,422 patients studied from 21 medical centers across the US from 2004 to 2010 with a median follow-up of 8 years from baseline colonoscopy found that, vs the no-adenoma group: 

    -- high risk adenoma: 7563 patients had a higher risk of colorectal cancer, with HR 2.61 (1.87-3.63) and related death with HR 3.94 (1.90-6.56)

    -- low risk adenoma: 10,978 patients had no significant increased risk of CRC, with HR 1.29 (0.89-1.88) and related death, with HR 0.65 (0.19-2.18) 

    -- with up to 14 years of follow-up, low risk adenomas were not associated with significantly increased risk of CRC or related deaths 

        -- they did exclude sessile serrated polyps, given the complexity of accurately assigning size and likely inconsistency of pathologists' diagnosis 

 

-- on a related note, the US Preventive Services Task Force is currently reviewing their colon cancer screening guidelines, with public comment until November 23, including a grade B recommendation for colorectal cancer screening in adults age 45 to 49 (reflecting the documented shift in colorectal cancers to this younger population). See https://uspreventiveservicestaskforce.org/uspstf/draft-recommendation/colorectal-cancer-screening3. will review recommendations after they are formally endorsed

so, these are welcome changes. it seems that colonoscopy leads to very high detection rates for tubular adenomas (in about 1/2 of colonoscopies....). and the above studies confirm that having a couple of small ones has a very similar outcome to having a normal colonoscopy, hence the longer time interval recommended for repeat colonoscopies. Given the relative equipoise from prior studies/recommendations regarding general screening colonoscopy and FIT tests (the latter being much easier on patients/no need for intestinal cleanout, though needs to be done yearly), many patients have preferred FIT test screening. in light of the studies above suggesting that those with low-risk adenomas have essentially the same prognosis as with a normal colonoscopy, the next logical step would be to allow FIT screening as well as routine colonoscopy for their follow-up. we'll see if these guidelines change....

relevant prior blogs

http://gmodestmedblogs.blogspot.com/2019/11/colon-adenoma-polyp-followup.html   presents a microsimulation model of lifetime risk of CRC cases and deaths with different colonoscopy follow-up strategies, for patients at age 50, 60, or 70, from the Natl Cancer Institute

http://gmodestmedblogs.blogspot.com/2018/04/2-new-colorectal-cancer-screening.html  reviews the WHO and US Multi-Society Task Force recommendations for colon cancer screening (by the way, the Canadian guidelines recommend FIT screening every 2 years vs the US guidelines of yearly)

http://gmodestmedblogs.blogspot.com/2019/11/colon-ca-screening-per-acp.html reviews the recent Am College of Physicians colon cancer screening guidelines, also recommending FIT testing every 2 years

geoff

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