34 / 78
34
Vol. 66, No. 4 2015
Northeast Florida Medicine
DCMS online
. org
Inflammatory Bowel Disease
The recommendation of colectomy for high-grade and
low-grade dysplasia implies dysplasia may be endoscopically
invisible. There is broad acceptance that “invisible” high-
grade dysplasia is an indication for colectomy. For low-grade
dysplasia, recommendations are more controversial. If low-
grade dysplasia is found in one area on initial colonoscopy,
closer surveillance colonoscopy is acceptable. If it is found
in more than one area or on subsequent colonoscopies,
colectomy is generally recommended.
5
The most controversial area in dysplasia detection is in the
definition of a dysplasia associated lesion or mass (DALM).
The controversy rests inwhether a trueUC-related dysplastic
lesion can be distinguished from a sporadic (non-colitis
associated) adenoma. The potential consequences of failure
to distinguish are extreme, ranging from an unnecessary
colectomy to a missed opportunity to cure CRC. Two
studies have found that it is safe to simply remove lesions
that are sporadic “adenoma like.” In a study of 48 UC
patients with an average duration of 25 years, 70 polyps
were removed and no cancers developed after 4.1 years of
follow-up.
16
Similarly, in a surveillance group with a UC
duration averaging 10 years, no cancers developed after 42
months with one case of low-grade dysplasia.
17
The decision
to remove or refer for colectomy is based on endoscopic
appearance and patient characteristics. Lesions that are
outside an area of colitis, pedunculated or discrete (clear
borders) can safely be removed. Biopsies should be taken
from around the lesion and if dysplasia is found the patient
should be referred to a specialized center for consideration of
colectomy. Older patients are more likely to have sporadic
adenomas, while patients with PSC are more likely to have
UC related dysplasia.
Does Colorectal Cancer
Surveillance Prolong Survival?
ACochrane analysis published in2008 foundno conclusive
benefit of UC surveillance for CRC survival.
18
Evidence was
indirect with, at best, trends toward improved survival that
did not reach statistical significance. There was an apparent
benefit in that CRC diagnosed with surveillance tended to
be at an earlier stage resulting in better survival. However, as
the authors point out, this may simply be due to lead-time
bias where survival appears to be prolonged only because the
cancers were diagnosed earlier.The authors did conclude that
“lower quality evidence, however supports the continued use
of some formof surveillance for these patients.”This analysis
was based largely on studies that used standard definition
rather than high definition colonoscopy and did not utilize
advanced imaging techniques.
Advanced Endoscopy Imaging:
Chromoendoscopy and
The New Era of Surveillance
Current surveillance methods predominantly rely on
a cumbersome, time-consuming and expensive process
of multiple randomly obtained (non-targeted) mucosal
biopsies to detect dysplasia. Standard colonoscopy alone is
imperfect, lacking acceptable sensitivity and specificity.
19,20
Chromoendoscopy (CE) involves the spray application of
dye solutions, typically indigo carmine or methylene blue,
to the colonic mucosa.
21
Prior to chromoendoscopy, the colon is washed with
water on insertion of the scope to clear any debris and
to provide an adequate colonic preparation. Either dye is
then mixed in water at concentrations ranging from one to
two percent and sprayed on the colon on withdrawal from
the cecum (Figure 1). Obtaining biopsies of visible lesions
with either dye improves dysplasia detection. Methylene
blue staining differentiates non-neoplastic and neoplastic
lesions with a sensitivity of 93 percent and specificity of
93 percent.
22
Dysplasia detection rates are up to fourfold
higher with CE.
23,24
Despite convincing data from several well-designed
studies, CE has not been universally accepted. It has been
recommended by the Crohn’s and Colitis Foundation of
America and the American Gastroenterological Associa-
tion,
12,25
but not by the American College of Gastroenter-
ology (ACG).
26
The ACG chose not to advocate routine
use of this technique because of lack of knowledge of the
natural history of lesions seen only under CE. The ACG
has suggested that CE may have benefit for “high risk”
patients. To understand whether removal of small lesions
seen with CE decreases the risk of subsequent colon cancer
would require a large natural history study that is unlikely
to be performed in the near future.
Figure 1.
Chromoendoscopy improves dysplasia
detection and lesion resolution. A colonic dysplastic lesion
seen with high definition white light (A) and then with
chromoendoscopy (B) is shown.