Report in English with a Dutch summary (KCE reports 45A)

KCE reports vol.45 Screening for Colorectal Cancer 35
Table 5: Evidence Supporting the Adenoma Carcinoma Sequence in
Colorectal Cancer 63
1. Adenomas and carcinomas are frequently contiguous
2. The anatomical distribution of adenomas and carcinomas is similar
3. Adenomas > 2 cm in diameter have a 50% risk of harboring invasive malignancy
The prevalence of adenomas is similar to that of carcinomas, and the average age of
4.
adenoma patients is about five years younger
In about one third of all surgical specimens resected for carcinoma, synchronous
5.
adenomas will be found
6. Familial adenomatous polyposis (FAP) is unequivocally premalignant
Adenomas and carcinomas share similar patterns of chromosomal abnormality and
7.
8.
genetic mutation
There is indirect but strong evidence that colonoscopy and polypectomy are associated
with a reduced incidence of carcinoma
In effect, measures which reduce the incidence and prevalence of adenomas
may result in a subsequent decrease in the risk of colorectal cancer 64. In
addition, the National Polyp Study (US) data suggest that adenoma prevalence
results from a dynamic process of both formation as well as regression of
adenomas 65.
All publicatons 59, 60, 66, 67, 61, 62 concur on:
1. Patients with only one or two tubular adenomas < 1 cm with
only low-grade dysplasia should have their next follow-up
colonoscopy in 5 to 10 years. The precise timing within this
interval should be based on other clinical factors (such as prior
colonoscopy findings, family history, and the preferences of the
patient and judgment of the physician).
2. Patients with 3 to 10 adenomas, or any adenoma > 1 cm, or any
adenoma with villous features, or high-grade dysplasia should
have their next follow-up colonoscopy in 3 years provided that
piecemeal removal has not been done and the adenoma(s) are
completely removed.
3. Patients who have more than 10 adenomas at one examination
should be examined at a shorter (< 3 years) interval established
by clinical judgment, and the clinician should consider the
possibility of an underlying familial syndrome.
4. Patients with sessile adenomas 67 that are removed piecemeal
should be considered for follow up at short intervals (2 to 6
months) to verify complete removal. Once complete removal
has been established, subsequent surveillance needs to be
individualized based on the endoscopist s judgment.
Completeness of removal should be based on both endoscopic
and pathologic assessments.
5. Patients with small rectal hyperplastic polyps should be
considered to be at average risk, and therefore the interval
before the subsequent colonoscopy should be 10 years. An
exception is patients with a hyperplastic polyposis syndrome 66.
They are at increased risk for adenomas and colorectal cancer
and need to be identified for more intensive follow up.