Introduction
Five subtypes of colorectal polyps have been described: hyperplastic polyps (HP),
sessile serrated lesions (SSL), adenomas with a very low risk of undetected adenocarcinoma,
adenomas with a high risk of undetected adenocarcinoma and superficial adenocarcinoma
(intramucosal or submucosal invasion under 1000 microns (sm1), and invasive adenocarcinomas
(submucosal involvement over 1000 microns).
In theory, therapeutic approach differs according to type of polyp. Whereas HP do
not require resection when their diameter is less than 10 mm [1]
[2], SSL and adenomas with a very low risk of undetected adenocarcinoma must be completely
resected to avoid recurrence, and for these en bloc resection with free margins is
preferable but not mandatory. In adenomas with a high risk of undetected adenocarcinoma
and superficial adenocarcinomas, endoscopic en bloc resection with negative margins
(R0 resection) is preferred to piecemeal endoscopic mucosal resections (EPMR), as
it allows proper pathological assessment and avoids local recurrence, despite this
being associated with higher risk of complication [3]. For invasive adenocarcinomas, surgery with lymphadenectomy and/or chemotherapy
but not endoscopic treatment is recommended.
Accurate real-time characterization of colorectal polyps during colonoscopy is of
paramount importance as it will allow the most appropriate treatment to be chosen.
At least seven classifications are currently used to characterize colorectal polyps.
The macroscopic pattern is described by the Paris Classification [4] and by the laterally spreading tumors (LST) classification [5]. The pit pattern is described by Kudo’s classification [6] (requiring use of indigo carmine with or without crystal violet dying), the NICE
classification (NBI International Colorectal Endoscopic) [7], and the JNET classification (Japan NBI Expert Team) [8]. The vascular pattern is described by Sano’s [9], JNET [8], and NICE [7] classifications. SSL are characterized by the WASP (Workgroup serrAted polypS and
Polyposis) criteria [10]. All these classifications have limitations, and none is sufficiently comprehensive
to describe and characterize alone all five subtypes of colorectal lesions. For instance,
the NICE classification [7] is effective in differentiating HP (type 1) from invasive carcinoma (type 3) from
adenomas and superficial carcinoma (type 2). This classification does not differentiate
between adenomas with a very low risk of undetected adenocarcinoma and those with
a high risk of undetected adenocarcinoma and superficial adenocarcinomas, although
their treatment responds to different constrains. The JNET Classification [8] differentiates low-risk adenomas from superficial invasive carcinoma with a good
accuracy (77.1 % for type 2A and 78.1 % for type 2B). However, it does not take into
account the macroscopic type of laterally spreading tumors, in which invasive adenocarcinoma
may exist despite the lack of an irregular pattern, as demonstrated by Yamada et al.
(21.1 % for LST NG, 15.0 % for LST G with large nodule or depression) [11] The SSLs are only described in WASP classification with a good accuracy [10].
We therefore merged criteria for these seven validated classifications into a single
table named COlorectal NEoplasia Endoscopic Classification to Choose the Treatment
(CONECCT; [Fig. 1]) with a pragmatic proposal of the most appropriate treatment based on each subtype
of colorectal polyp and on the European Society of Gastrointestinal Endoscopy guidelines
(ESGE) [3]
[12], The current study aimed to assess the impact of a teaching program, using this
newly created table, in terms of accuracy of polyp characterization, and choice of
appropriate treatment.
Fig. 1 CONECCT table. The words in bold are the ones that require particular attention when
analyzing lesions.
Methods
Design
We conducted a prospective multicenter study including trainees (gastroenterology
fellows and attending physicians) who were evaluated before, and immediately and at
3 to 6 months after a teaching course on characterization and treatment of colorectal
lesions using the CONECCT table.
CONECCT table
The CONECCT table was created using a combination of criteria used in the aforementioned
classifications (Paris4, LST5, NICE7, Kudo6, WASP10, JNET8, Sano9), by physicians
from the research and development committee of the Société Francaise d’Endoscopie Digestive (SFED; [Fig. 1]). Characterization of the lesions was based on the macroscopic aspect, the color
on narrow band imaging (NBI), vascular pattern and pit pattern. To characterize a
polyp using the CONECCT table, at least two imaging conditions are required. On the
one hand, a white-light distant image of the polyp is required to analyze its macroscopic
aspect. On the other hand, a virtual chromoendoscopy-ready image with magnification,
if possible, is needed to analyze the microscopic structures of the polyps and identify
diagnostic criteria associated with a risk of neoplasia. For each subtype of colorectal
polyp, this table suggested a treatment, based on the latest guidelines from the ESGE
[3]
[12].
HP (CONECCT IH) are mostly seen in the rectum and the sigmoid. These lesions have
the following features based on the NICE classification [7]: color is same or lighter than background, vessels are lacking or isolated lacy
vessels coursing across the lesion that do not surround the pits and the surface pattern
has dark or white spots of uniform size or homogeneous absence of pattern. IH are
usually small and numerous. Risk of progression to cancer is null and guidelines do
not recommend resection of these polyps after proper identification using virtual
chromoendoscopy (NBI) if they are less than 5 mm [12].
SSLs (CONECCT IS) are characterized using the WASP classification,[10] two of the following criteria are required: indistinctive border, clouded surface,
irregular shape and dark spots inside the crypts. SSL are frequently covered by a
yellowish mucus cap, and although not used in the WASP classification [10] as a diagnostic criterion, this was added to the table to aid recognition. For SSL,
resection is recommended given the risk of cancer (via BRAF mutation). However, most of these lesions are not dysplastic and reports of transformed
SSL are rare. Thus, low-risk endoscopic resection methods without aiming for completely
free margins are recommended (preferably En Bloc) to reduce the risk of perforation
[12].
Adenomas CONECCT IIA have a very low risk of undetected adenocarcinoma (< 1 %). They
present a various array of features. According to the Paris classification, the macroscopic
shape can be sessile (Is), pedunculated (Ip), or flat (IIa or IIb) [4]. The vascular pattern is that of meshed regular vessels surrounding the pits (Sano
II) [9]. The pit pattern based on Kudo’s classification can be of type IIIs, IIIL, or IV
[6]. These lesions lack any of the criteria seen in adenomas with a high risk of undetected
carcinoma (CONECCT IIC), superficial (CONECCT IIC) and invasive carcinomas (CONECCT
III). As for SSL, these lesions should also be resected with low-risk endoscopic procedures.
Of note, granular homogenous laterally spreading tumor (LST G) with no macro nodule
are considered at very low risk of undetected adenocarcinoma when smaller than 4 cm
and can be resected with EPMR as recommended by the ESGE guidelines [12].
Adenomas with a high risk of undetected adenocarcinoma and superficial adenocarcinomas
(CONECCT IIC) constitute the fourth subtype of colorectal polyp. Adenomas with a high
risk of undetected adenocarcinoma are lesions without clear evidence of adenocarcinoma,
but with a high risk of invasive carcinoma because of their macroscopic aspect. Non-granular
LST (LST NG) and LST G with large nodules (> 1 cm) for instance have a high risk of
invasive carcinoma, over 15 % [5]. Given this risk, en bloc resection is recommended, as this allows correct pathological
examination that, in turn, avoids underestimation of the depth of invasion. Superficial
adenocarcinomas are lesions with evidence of neoplasia but no clear features of deep
submucosal invasion. For instance, a slightly depressed lesion (Paris classification
IIc) [4], the lake of uniformity of the vessels and the high density of capillary vessels
without avascular areas (Sano’s IIIa) [9] or presence of an irregular pit pattern (irregular mucosal pattern without any amorphous
area and without demarcation line; Kudo’s type V) [6] are associated with a high risk of invasive components and should be resected en
bloc with free margins, to allow pathological examination and curative resection [12]. (Irregular mucosal and vascular pattern also define type 2B of the JNET classification
[8].)
Invasive adenocarcinomas (CONECCT III) typically presents with features associated
with a high risk of deep submucosal invasion such as an excavated shape (III Paris
classification [4]), nodule or pseudo mass within a depressed LST NG, avascular areas (Sano’s IIIB)
[9] loss or decrease of pits with an amorphous structure (Kudo Vn) or an irregular pit
pattern in a demarcated area (Vi invasive) [6]. These avascular and amorphous features are also used in the NICE (type 3) and JNET
classifications (type 3) [8]. In such cases, endoscopic procedures are not indicated. Patients must be referred
to an oncologist.
Trainees and teaching program
Fellows from the seven French districts (Paris region, Northwest, Northeast, Southwest,
Southeast, West, and East) were invited to participate in the study as ‘trainees’
after signed consent. In France, gastroenterology fellows are postgraduate (post-medical
school) students specializing in hepatology, gastroenterology, and endoscopy. Attending
physicians were also invited to participate by the French society of digestive endoscopy
(Société Française d’Endoscopie Digestive – SFED), via email, newsletter, website publications, and during nationwide meetings.
Teaching program was divided into two training sessions occurring at least 3 months
apart (this design was chosen for feasibility reasons as well since gastroenterology
fellows in France are available all together only twice a year). Each trainee created
an identification number (ID) from his/her initials and date of birth. For each training
session, the trainee was requested to indicate his/her ID on the reply form to match
their identity with the test answers. Trainees were excluded from the first training
session if they did not complete each of the two required tests (pretest and post-test)
in the first training session, and from the second training session analysis at 3
to 6 months (T3 M) if their ID could not be matched with that used in the first training
session.
For each training session, the different tests (pretest, post-test, and T3 M) were
taken either in person on paper or online (Google Forms, Google Inc., California,
United States). Images of the lesions were projected by a video projector if the training
session was done in a classroom, otherwise they appeared on their computer screen
if the participant answered online. Participants had as much time as they wanted to
analyze the images.
First training session
The first training session was divided into five steps:
-
Step 1: Evaluation of awareness and clinical use of the seven classifications used in the
CONECCT table (Paris [4], LST [5], NICE [7], Kudo [6], WASP [10], JNET [8], Sano [9]).
-
Step 2 (pre-test): Histological prediction and treatment choice for 20 colorectal polyps. To predict
histology, trainees were provided with one to five images per lesion, at least one
of which was taken with NBI, the rest being taken in WL; lesions were not dyed. The
location in the colon of the polyps were provided.
-
Step 3: Standardized 30-minute teaching course given by French endoscopy experts (endoscopists
currently performing advanced endoscopic diagnosis and ESD) from the research and
development committee of the SFED and describing the content of the CONECCT table,
including the criteria for each of the five subtypes of colorectal polyps with several
examples, as well as the recommended treatments.
-
Step 4 (post-test): Identical to pretest, but frames in a different order. Of note, regarding histological
prediction, trainees had to reply using the CONECCT table that was provided to them.
For both tests, the breakdown of lesions was as follows: three HP, four SSLs, five
adenomas, four high-risk adenoma or superficial adenocarcinomas and four deep invasive
adenocarcinomas.
-
Step 5: At the end of the first training session, the group of trainees were informed of
the correct histological prediction and the treatment choice for each example but
did not receive individual feedback as to potential errors.
Second training session (T3 M)
Three to 6 months after the first training session, the trainees took the T3 M test
that consisted of still frames depicting a total of 40 colorectal polyps, including
the 20 polyps used during the first training session and 20 new polyps. The questions
were identical to those in the first training session and there was no additional
teaching course. The breakdown of lesions was as follows: seven HP, eight SSLs, nine
adenomas, eight high-risk adenomas or superficial adenocarcinomas and eight deep invasive
adenocarcinomas.
Evaluation of the trainees’ answers
For each individual frame, the answer was considered correct if the trainee chose
the correct histological prediction or treatment choice. Regarding histological prediction,
trainees chose among the following possibilities: HP, SSL, adenomas with a very low
risk of undetected adenocarcinoma, adenomas with a high risk of undetected adenocarcinoma
and superficial adenocarcinomas and deep invasive adenocarcinomas. The correct histological
prediction was defined by the histology report from a group of pathologists with expertise
in digestive histology for HP (CONECCT IH), SSL (CONECCT IS), and deep invasive adenocarcinoma
(CONECCT III). To differentiate adenomas with a very low risk of undetected adenocarcinoma
(CONECCT IIA) from adenomas with a high risk of undetected adenocarcinoma and superficial
adenocarcinomas (CONECCT IIC), the correct histological prediction was defined by
an expert group of endoscopists from the SFED (JR, MP, JJ) who arrived at a consensus
using the Delphi process, and for adenomas histology was used to detect presence of
adenocarcinoma and therefore distinguish between risk of undetected adenocarcinoma.
All resection pieces were fixed in buffered formalin and then embedded in paraffin
before being cut into 2-mm slices. Regarding treatment choice, trainees chose among
the following: no resection, resection (preferably en bloc, but piecemeal acceptable),
resection en bloc with free margins (R0) and surgery with lymphadenectomy. The correct
treatment choice was in accordance with ESGE guidelines for each type of lesion. Overtreated
lesions were defined as those for which a more invasive treatment than necessary was
proposed and undertreated lesions as those for which a less invasive treatment than
necessary was proposed.
Correctly predicted/treated lesions were those for which trainees chose both the correct
histological prediction and treatment choice. At 3 to 6 months, trainees were also
asked if they had used the CONECCT table on a daily basis since the first training
session, and if they considered CONECCT useful for histological prediction and treatment
choice in their routine practice.
Endpoints
The endpoints were:
-
histological prediction, treatment choice, and the mean of correctly predicted/treated
lesions between pretest (step 2) and post-test (step 4), as well as between the first
training session (pre-test and post-test) and the second training session 3 to 6 months
later (T3 M)
-
Comparison between gastroenterology fellows and attending physicians
-
Overall number of overtreated, undertreated lesions, and unnecessary surgeries
-
Analysis by histological subtype (test results, over and undertreated)
Statistical analysis
Baseline characteristics and outcome variables were described by the mean and range
for continuous variables, and by frequencies and percentages for categorical ones.
Comparisons of proportions between time points were performed using a mixed logistic
regression model to take into account the fact that an investigator classified multiple
lesions, and that lesions were classified at different time points. Comparisons of
proportions between investigators (fellows and attending physicians) were also performed
by mixed logistic regression models to take into account the fact that the same investigator
classified multiple lesions. P < 0.05 was considered statistically significant. All analyses were performed using
Excel software (Office, Microsoft, United States) or the R software (R Core Team 2018.
R: A language and environment for statistical computing. R Foundation for Statistical
Computing, Vienna, Austria. URL https://www.R-project.org/.)
Ethical concerns
All trainees received oral information about the study protocol and signed a written
consent for participation. The protocol followed the declaration of Helsinki and was
approved by the local ethics committee (Comité d’éthique du Centre Hospitalo-Universitaire
de Lyon).
Registration
The study was registered in the US National Clinical trial register under the number
NCT03455595.
Results
All training sessions took place between April 2017 and April 2018. A total of 419
gastroenterology fellows and attending physicians participated in the first training
session; 23 were excluded because they had not performed the post-test, and therefore
396 trainees were analyzed (275 GI fellows, 121 attending physicians; [Fig. 2]).
Fig. 2 Flowchart of the study.
A total of 302 gastroenterology fellows and attending physicians participated in the
second training session; 99 were excluded because of ID matching issues (n = 96, either
a failure to complete the ID or a change in the ID) or because the post-test during
the first training session had not been performed (n = 3), and therefore 203 trainees
were analyzed (137 GI fellows, 66 attending physicians; [Fig. 2]). Mean ± SD age of the gastroenterology fellows was 26.9 ± 1.9 years, and that of
attending physicians 43.8 ± 11.9 years.
First training session, step 1 results
The Paris classification was used by 63.4 % of trainees, 28.5 % used the NICE classification,
36.8 % used the Kudo classification, 10.9 % used the Sano classification, and 7.6 %
used the WASP classification. Overall, 1.5 % of the fellows and 9.9 % of the attending
physicians used all classifications while 47.2 % and 13.2 % used any of them.
Results in the first training session (pretest and post-test)
At post-test compared to pretest, there was a statistically significant improvement
in the mean proportion of correct histological prediction, from 60.5 to 76.2 % (+ 26.4 %,
P < 0.001), and correct treatment choice, from 61.1 to 77.4 % (+ 26.8 %, P < 0.001). Mean proportion of correctly predicted/treated lesions improved statistically
significantly, from 51.0 % to 74.0 % (+ 45.1%, P < 0.001). Trainees improved their performances between pretest and post-test in 86.6 %
of cases (343/396).
The pretest results of the attending physicians were statistically significantly better
than those of gastroenterology fellows (73.9 % vs. 54.6 % for the histological prediction,
69.9 % vs. 57.2% for the treatment choice, both P < 0.001). Mean improvement in post-test results for gastroenterology fellows was
statistically significantly higher than that for attending physicians (+ 34.8 % vs. + 11.1 %
for the histological prediction, 31.6 % vs. 17.9 % for the treatment choice, both
P < 0.001; [Table 1]).
Table 1
Overall results of histological prediction and treatment choice.
|
Histological prediction
|
Treatment choice
|
Well-predicted and well-treated lesions
|
|
Pre-T
|
Post-T
|
T3 M
|
Pre-T
|
Post-T
|
T3 M
|
Pre-T
|
Post-T
|
T3 M
|
|
Overall (%)
|
60.5
|
76.2
|
70.3
|
61.1
|
77.4
|
70.9
|
51.0
|
74.0
|
66.6
|
|
Fellows (%)
|
54.6
|
73.6
|
65.5
|
57.2
|
75.3
|
66.4
|
45.0
|
71.5
|
59.1
|
|
Attending physicians (%)
|
73.9
|
82.1
|
80.4
|
69.9
|
82.4
|
80.3
|
63.9
|
79.9
|
78.9
|
Pre-T, pretest; Post-T, Post-test; T3 M, second training session
Results in the second training session (T3 M)
At T3 M compared to pretest, there was a statistically significant improvement in
mean proportion of correct histological prediction, from 60.5 to 70.3 % ( + 16.2 %,
P < 0.001), and correct treatment choice, from 61.1 to 70.9 % (+ 16.0 %, P < 0.001). The mean proportion of correctly predicted/treated lesions improved statistically
significantly, from 51.0 % (4040/7920) to 66.6 % (5408 /8120; + 30.6 %, P < 0.001; [Table 1]). Trainees improved their performances between pretest and T3 M in 75.4 % of cases
(153 /203).
Mean proportion of correct answers for fellows and attending physicians were 73.6 %
and 82.1 % for histological prediction, respectively, and 75.3 % and 82.4 % for treatment
choice, respectively. Compared to the pretest results, a statistically difference
in favor of the T3 M was seen for the fellows ( + 34.8 % and + 31.6 %, both with P < 0.001) and for the attending physicians (+ 11.1 % and + 17.9 %, both with P < 0.001).
Decrease in the mean proportion of correctly predicted/treated lesions between the
end of the first training session (post-test) and the second training session (T3 M)
was more pronounced for the fellows than for the attending physicians (–17.3 % for
the fellows vs –1.3 % for the attending physicians, P < 0.001; [Table 1]).
Overall number of over and undertreated lesions and unnecessary surgeries
At post-test compared to pretest, there was a statistically significant reduction
in the number of overtreated lesions, from 30.1 % (2383/7920) to 15.5 % (1227/7920;
– 48.8 %, P < 0.001) and in the number of undertreated lesions, from 8.0 % (633/7920) to 6.7 %
(530/7920; – 16.3 %, P < 0.001). Also, colorectal lesions were statistically significantly more overtreated
than undertreated (30.1 vs 8.0 %, P < 0.001).
At T3 M compared to pretest, there was a statistically significant reduction in the
number of overtreated lesions, from 30.1 % to 18.5 % (1504 /8120; – 38.5 %, P < 0.001). There was a statistically significant improvement in the number of undertreated
lesions, from 8.0 % to 9.7 % (787 /8120; + 21.1 %, P = 0.01).
The number of unnecessary surgeries was statistically significantly reduced, from
8.6 % (683/7920) at pretest to 6.3 % (496/7920) at post-test (–27.4 %, P < 0.001), to 5.7 % (467/8120) at T3 M (–33.7 %, P < 0.001).
Analysis by polyp subtype
Regarding lesions CONECCT IH, mean proportion of correctly predicted/treated lesions
was 62.0 % at pretest, 93.7 % at post-test and 73.7 % at T3 M. The differences were
statistically significant between pretest and post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.001; [Fig. 3]). Mean proportion of overtreated lesions were 35.9 % at pretest, 5.5 % at post-test
and 25.2 % at T3 M. Differences were statistically significant between pretest and
post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.001; [Fig. 4]).
Fig. 3 Mean proportion of correctly predicted/treated lesions by subtype of polyp.
Fig. 4 Mean proportion of overtreated lesions by subtype of polyp.
Regarding lesions CONECCT IS, mean proportion of correctly predicted/treated lesions
were 33.4 % at pretest, 71.1 % at post-test and 58.6 % at T3 M. Differences were statistically
significant between pretest and post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.001; [Fig. 3]). Mean proportion of overtreated lesions were 45.5 % at pretest, 22.1 % at post-test
and 30.6 % at T3 M. Differences were statistically significant between pretest and
post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.05; [Fig. 4]). Mean proportion of undertreated lesions was 3.7 % at pretest, 2.0 % at post-test
and 2.7 % at T3 M. Differences were only statistically significant between pretest
and post-test (P < 0.001; [Fig. 5]).
Fig. 5 Mean proportion of undertreated lesions by subtype of polyp.
Regarding lesions CONECCT IIA, mean proportion of correctly predicted/treated lesions
were 42.8 % at pretest, 67.7 % at post-test and 70.1 % at T3 M. Differences were statistically
significant between pretest and post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.001; [Fig. 3]). Mean proportion of overtreated lesions were 36.5 % at pretest, 23.0 % at post-test
and 18.5 % at T3 M. Differences were statistically significant between pretest and
post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.001; [Fig. 4]). Mean proportion of undertreated lesions was 3.5 % at pretest, 1.7 % at post-test
and 2.5 % at T3 M. Differences were statistically significant between pretest and
post-test (P < 0.001) and between pretest and T3 M (P < 0.01; [Fig. 5]).
Regarding lesions CONECCT IIC, mean proportion of correctly predicted/treated lesions
were 42.8 % at pretest, 57.6 % at post-test and 52.2 % at T3 M. Difference were statistically
significant between pretest and post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.01; [Fig. 3]). Mean proportion of overtreated lesions were 32.4 % at pretest, 22.5 % at post-test
and 18.6 % at T3 M. Differences were statistically significant between pretest and
post-test (P < 0.001), pretest and T3 M (P < 0.001) and post-test and T3 M (P < 0.01; [Fig. 4]). Mean proportion of undertreated lesions was 16.0 % at pretest, 17.2 % at post-test
and 25.3 % at T3 M. Differences were not statistically significant ([Fig. 5]).
Regarding lesions CONECCT III, mean proportion of correctly predicted/treated lesions
were 80.3 % at pretest, 86.6 % at post-test and 78.8 % at T3 M. Differences were only
statistically significant between pretest and post-test (P < 0.001; [Fig. 3]). Mean proportion of undertreated lesions were 15.9 % at pretest, 12.2 % at post-test
and 17.2 % at T3 M. Difference was only statistically significant between pretest
and post-test (P < 0.001; [Fig. 5]).
Value of the CONECCT TABLE
At T3 M, 87.0 % of the trainees considered the CONECCT table to be a useful tool to
predict histology of a colorectal polyp, and 89.0 % for choosing a treatment. At T3 M,
40.3 % of trainees routinely used CONECCT.
Discussion
The current study found that a teaching program of the CONECCT table is effective
in improving histological prediction and treatment choice for colorectal polyps in
both fellows and attending physicians specializing in gastroenterology. The benefits
of this program were found regardless of the type of lesion and personal experience.
In clinical practice, this improvement yielded a reduction of under- and overtreatment
of colorectal polyps and could thus potentially impact treatment of these lesions.
Furthermore, there was a persistent statistically significant improvement after 3
to 6 months.
For each subtype of polyps, there was a statistically significant improvement between
pretest and post-test in histological prediction and treatment choice. These results
are encouraging, particularly for CONECCT IH lesions, because the minimal 95 % threshold
of correct characterization required for the “not-resect” strategy of the ESGE guidelines
is almost reached in the post-test [12]. On the other hand, performance for characterization of the lesions CONECCT IIA
are still far from the same 95% threshold of correct characterization using NBI to
introduce the “Resect and Discard” strategy of the ESGE guidelines in routine practice
[12]. SSL were the least correctly characterized before the teaching course and a minority
of trainees reported using the recent WASP classification [10]. The teaching program CONECCT allowed them to make statistically significant progress
in histology prediction of and treatment choice for these lesions. Endoscopic recognition
of the landmarks of superficial and invasive carcinoma is crucial. In cases of invasive
adenocarcinomas, potential resection is surgical to allow resection of both the invaded
colon and the potentially metastatic lymph nodes. The participants already characterized
and treated invasive cancers correctly before the program, but did improve at post-test.
Conversely, superficial adenocarcinomas (invasion limited to the mucosa or the first
1000 microns of the submucosa) have no risk of lymph node metastasis and, therefore,
overestimation of advancement of such cancerous lesions may lead to unnecessary surgery
[12]
[13] that is associated with 24 % morbidity and 0.5 % mortality [14]. Superficial adenocarcinomas are best addressed by en bloc endoscopic resection
with free margins, as it achieves a curative goal with organ preservation [3]
[15] and ESD is safer than surgery as it is associated with 5 % rate of perforation,
but less than 1 % of subsequent salvage surgery [16]
[17]. Endoscopic recognition of superficial adenocarcinomas is therefore key to reduce
the frequency of unnecessary surgery [14].
In the current study, CONECCT teaching program led to an improvement in histology
prediction and treatment choice for superficial adenocarcinomas. This diagnostic performance
is far from sufficient in this setting despite being an encouraging first step. Based
on all these considerations and also because participants regressed for each subtype
of polyp outside the lesions CONECCT IIA for which there is indeed a statistically
significantly progression, multiple training sessions with polyp recognition seem
warranted to achieve better diagnostic rates.
The current study found that fewer than 5 % of participants use all the classifications
necessary to predict histology of a polyp and thus choose the appropriate treatment.
Merging all these classifications as does the CONECCT table therefore seems important
even if having five types of lesions in one table may appear more complex. However,
it allows characterization of all types of colorectal polyps frequently found in clinical
practice.
There are several limitations to the current study. First, the criteria gathered in
the CONECCT table have been validated under different endoscopic conditions; certain
criteria have been validated using a zoom and virtual chromoendosocopy (JNET [8], NICE [7]), while others have been validated with indigo carmine and crystal violet dye (Kudo
Classification [6]). To use the CONECCT table would therefore require access, in real-time, to all
these conditions, which is not feasible, and in any case many of these modalities
are not very widespread in common practice in France.
This study demonstrates the value of such a tool, but it does not validate a new classification.
A prospective evaluation is ongoing to validate use of this table. Second, as mentioned
above, still frames (taken by expert endoscopists) were used herein. This signifies
that the detection process of colorectal lesions is bypassed. In clinical practice,
detection rates vary among endoscopists. Performance of the trainees was probably
overestimated given that certain lesions would potentially have been missed in real
life. Furthermore, the still frames used were taken by different endoscopists, thus
introducing variability regarding their quality, which in turn may have impacted characterization
during the training sessions. Third, the CONECCT table was not compared to a validated
classification (such as teaching tools). Lastly, we used the same still frames for
the pretest and post-test, introducing memorization bias, but we chose this design
to compare polyps with the same difficulty of histological prediction.
Conclusion
In conclusion, the CONECCT teaching program is effective in improving histological
prediction and treatment choice performance, regardless of the type of colorectal
polyp considered, and for both gastroenterology fellows and attending physicians.
Despite these encouraging results, further sessions are needed to maintain or improve
the level of participants. A validation study for this table is currently underway.
