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Malignant Colon Polyps
AndreaM.Petrucci andMarianaBerho
62
Refer toAlgorithm inFig. 62.1
A. Non-invasive Polyps
Carcinoma in situ, high-grade dysplasia
or intramucosal adenocarcinoma are all
terms used to describe an adenomatous polyp
displaying a high degree of cellular and
architectural atypia that is conned to the
lamina propria. The mucosal lining of the
colon is divided into 3 components: the epithelium, the lamina propria and the muscularis mucosa. While in adenomas with high
grade dysplasia/carcinoma in situ the lamina
propria is not involved by tumor, intramucosal adenocarcinoma is characterized by spillage of the neoplastic cells beyond the
basement membranes of the colonic crypts
into the lamina propria. Due to absence of
lymphatics in the lamina propria of the colon
and rectum, none of these lesions have metastatic potential. The TNM classication
groups these lesions into the Tis category and
although they have the potential for invasion
into the wall of the colon/rectum, polypectomy is sufcient if completely resected.
A. M. Petrucci
Department ofColorectal Surgery, Cleveland Clinic
Florida, Weston, FL, USA
M. Berho (*)
Department ofPathology, Cleveland Clinic Florida,
Weston, FL, USA
e-mail: berhom@ccf.org
B. Malignant Polyps
A “malignant” polyp is dened as the presence of adenocarcinoma that extends beyond
the basement membrane. It is important to
assess specic characteristics of the polyp in
order to decide whether further, more aggressive treatment is needed for adequate removal.
Invasive polyps can be pedunculated (C) or
sessile (D). Pedunculated polyps contain a
head, neck and stalk whereas sessile polyps
are at. In addition to the morphology of the
polyp, important histopathological features
including grade of differentiation, the presence of lymphovascular invasion, perineural
invasion or tumor budding as well as inadequate resection margins (<2 mm) all play a
very important role in predicting more aggressive disease in invasive polyps which will be
discussed later.
C. Pedunculated Polyps
Adenocarcinoma in a pedunculated polyp
is differently managed according to the location of the invasive cancer in the polyp. The
Haggitt’s classication was rst described by
Haggitt et al. in 1985 and is used to assess
adenocarcinoma that invades into the submucosa in pedunculated polyps. It is a 4-level
classication system where levels 1 through 4
indicate adenocarcinoma limited to the head,
neck, stalk and base of the polyp respectively
(Fig.62.2). Pedunculated polyps of Haggitt’s
level 1–3 have a <1% risk of lymph node
metastasis therefore can be managed by
© Springer Nature Switzerland AG 2020
S. R. Steele etal. (eds.), Clinical Decision Making in Colorectal Surgery,
https://doi.org/10.1007/978-3-319-65942-8_62
479
480
Adenocarcinoma
Sessile adenoma
Le
Le
Le
Le
Pedunculated adenoma
Le
Fig. 62.1 Algorithm for malignant colonic polyps
A. M. Petrucci and M. Berho
vel 0
Propria
Adenomatous
epithelium
Normal
colonic
mucosa
Muscularis
mucosae
Adenocarcinoma
Submucosa
Muscularis
Propria
Subserosal connective tissue
vel 1
vel 2
vel 3
vel 4
Submucosa
Muscularis
Subserosal connective tissue
Fig. 62.2 Demonstration of the different levels of invasion between a pedunculated (right) and a sessile (left) adenoma.
(With permission Nivatvongs 2002 © Elsevier)
SM1 SM2 SM3
62 Malignant Colon Polyps
481
simple polypectomy, given that they have
favorable histological features. Haggitt’s
level 4 is equivalent to a sessile polyp and
they are managed similarly. Any suspicious
polyp should be tattooed at the site in order to
locate it as needed.
D. Sessile Polyps
Adenocarcinoma in a sessile polyp is usually managed with surgical resection, to
include a formal lymphadenectomy given the
correlation between the level of invasion
with the risk of further lymph node involvement. The level of invasion is characterized
by the Kikuchi classication, which divides
the submucosa into three depths of involvement: sm1 describes penetration of the upper
third of the submucosa, sm2 involves the
middle third and sm3 describes deep invasion to the lower third level, abutting the
inner surface of the muscularis propria
(Fig. 62.3). Tumor extending to the lower
third were found to have up to a 23% risk of
lymph node metastasis, hence the need for a
formal bowel resection regardless if they
were completely excised or removed piecemeal. It may not always be possible for the
pathologist to assess the different levels of
submucosal invasion depending on the quality of the specimen that is provided. A recent
systematic review showed that submucosal
invasion >1 mm corresponded with higher
rates of lymph node metastasis, hence the
need for formal surgical resection. Moreover,
it has recently been suggested that the area of
tumor involvement in which both width and
depth of invasion are considered may be a
better way to stratify risk of lymph node
metastasis.
E. Features
As mentioned earlier, there are many factors that play a signicant role in the management of malignant polyps. Size, morphology,
margin status, degree of differentiation and
histopathological features including lymphovascular and perineural invasion and tumor
budding are all carefully assessed since they
are all predictors of more aggressive tumors.
Polyps <5mm in size are usually benign; those
ranging from 1.5 to 3.5cm carry up to a 43%
risk of malignancy and should be approached
with caution. Margin status is a concern since
it correlates with recurrence; polyps with
involved margins or margins <1mm from the
cut edge correlates with recurrences ranging
from 21 to 33% therefore the acceptable margin should be > or = to 2mm. Traditionally, the
grades of differentiation were described as
grade 1 (well- differentiated), grade 2 (moderately-differentiated), grade 3 (poorly differentiated, including intestinal-type, signet ring
cell or mucinous adenocarcinoma) and grade 4
(undifferentiated, including medullary carcinomas with high microsatellite instability).
More recently the College of American
Pathologists has recommended to categorize
grade of differentiation in colorectal tumors
into low grade (well and moderately differentiated adenocarcinoma) and high grade (poorly
differentiated and undifferentiated adenocarcinoma). The degree of differentiation correlates
Submucosa
Fig. 62.3 Levels of submucosal invasion in a malignant sessile polyp. With author’s permission. (With permission
Nivatvongs 2002 © Elsevier)
482
A. M. Petrucci and M. Berho
with lymph node involvement. Blumberg etal.
looked at pathological factors and the risk of
lymph metastasis in rectal cancer and found
that well-and -moderately differentiated
tumors had a 14% risk of lymph node metastasis whereas the risk increased to 30% for
poorly differentiated lesions. Lymphovascular
invasion is an important prognostic factor. The
lymphatic channels are usually found in the
supercial submucosa and within the muscularis mucosa, which is why early lesions within
the mucosa have a very low risk of lymph node
involvement. Blumberg etal. also found that
when lymphovascular invasion is present in a
malignant polyp, there is a 33% chance of
lymph node metastasis whereas those without
lymphovascular invasion only had a 14% risk
of positive nodes making this marker a poor
prognostic factor. Although tumor budding,
which refers to a small clusters of undifferentiated cancer cells, has been found to be a poor
prognosticator, its utility in clinical practice is
limited due to the lack of standardization in the
pathological assessment.
In addition, microstaging of malignant
polyps to include the depth and width of
malignant invasion helps predict lymph node
metastasis. Ueno etal. showed that a depth of
≥2000 um and a width≥ of 4000 um correlated with a 18.2% and a 17.1% risk of lymph
node metastasis respectively, compared to a
<5% risk in polyps with invasion below these
values, making these useful histopathologic
features to consider.
F. Surveillance
According to the 2016 National
Comprehensive Cancer Network (NCCN)
guidelines, surveillance after a polypectomy
for Tis/T1N0M0 malignant lesion consists of
a colonoscopy at 1year following removal. If
at the time of colonoscopy, there is no sign of
recurrence or advanced adenoma, the interval
can be extended to 3years followed by every
5years after that (NCCN).
G. Resection
Colectomy can be performed either open
or laparoscopically, depending on the level
of experience of the surgeon, and should
include a formal lymphadenectomy, includ-
ing the identication of lymph nodes at the
origin of the feeding vessel. Any suspicious
node seen during surgery outside of the
resection margins should be removed and
sent to pathology as well. The requirements
for N staging consist of the identication of
a minimum of 12 lymph nodes in order to be
considered a complete and adequate resection (NCCN).
Suggested Reading
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LD.Prognostic factors in colorectal carcinomas arising in adenomas: implications for lesions removed
by endoscopic polypectomy. Gastroenterology.
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tal polyps. Surg Clin North Am. 2002;82(5):959–66.
Ramirez M, Schierling S, Papaconstantinou HT, Thomas
JS.Management of the malignant polyp. Clin Colon
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Suzuki T, Sadahiro S, Mukoyama S, Ishikawa K, Yasuda
S, Tajima T, et al. Risk of lymph node and distant
metastases in patients with early invasive colorectal
cancer classied as Haggitt’s level 4 invasion: image
analysis of submucosal layer invasion. Dis Colon
Rectum. 2003;46(2):203–8.
Ueno H, Mochizuki H, Hashiguchi Y, Shimazaki H, Aida
S, Hase K, etal. Risk factors for an adverse outcome in
early invasive colorectal carcinoma. Gastroenterology.
2004;127(2):385–94.
Colonic Conditions: Adenomatous Polyps
StevenA.Lee-Kong andP.RaviKiran
63
Refer toAlgorithm inFig. 63.1
A. The association between colorectal adenoma-
tous polyps and colorectal cancers (CRC)
was rst described by Lockhart-Mummery
and Dukes in 1927. This association set the
stage for the later recognition that adenomatous tissue is a precursor to the development
of CRC. The “adenoma to carcinoma”
sequence was further elucidated by the identication of somatic mutations associated
with this progression by Vogelstein etal. in
1988. These authors analyzed both colorectal
adenomas of varying size and carcinomas for
somatic mutations in known colorectal
cancer- associated genes. Mutations in ras
genes were more commonly identied in
large adenomas and cancers as compared to
smaller adenomas. In advanced adenomas
and carcinomas, as compared to smaller adenomas, chromosomal sequences were also
lost in chromosomal regions associated with
S. A. Lee-Kong
Department ofSurgery, Columbia University,
New York, NY, USA
P. R. Kiran (*)
Mailman School ofPublic Health, Columbia
University Medical Center, NewYork, NY, USA
Center forInnovation andOutcomes Research,
NewYork Presbyterian Hospital/Columbia University
Medical Center, NewYork, NY, USA
e-mail: rpk2118@cumc.columbia.edu
cancer. These results helped to solidify our
understanding of the step-wise development
of colorectal cancer, involving both oncogene
activation and loss of tumor suppressor gene
activity.
B. The National Polyp Study, published in 1993,
provided further evidence for the progression
of adenomatous polyps to colorectal cancer.
In this study, patients who underwent screening colonoscopy and polypectomy of histologically proven adenomatous polyps were
compared to reference groups of patients for
whom adenomatous polyps were not
removed. The authors found that patients who
underwent polypectomy had a lower-thanexpected incidence of colorectal cancer when
compared to the reference groups. This study
underscored the importance of screening
colonoscopy for the prevention of colorectal
cancer.
C. Guidelines which suggest a colonoscopy
screening algorithm are published by the
National Comprehensive Cancer Network
(NCCN), last updated in 2016. Initial screening for average risk individuals (no prior history of adenomatous polyp or colorectal
cancer, no family history of colorectal cancer and no personal history of inammatory
bowel disease) should start at 50 years of
age. Individuals with any of the above conditions should be screened based on NCCN
guideline suggestions. Special consideration
© Springer Nature Switzerland AG 2020
S. R. Steele etal. (eds.), Clinical Decision Making in Colorectal Surgery,
https://doi.org/10.1007/978-3-319-65942-8_63
483
484
Fig. 63.1 Algorithm for colonic adenomatous polyps
S. A. Lee-Kong and P. R. Kiran
should be given to individuals in whom a
high-risk colorectal cancer syndrome may
exist. These categories include Lynch
Syndrome, Hereditary Nonpolyposis
Colorectal Cancer (HNPCC), classical or
attenuated Familial Adenomatous Polyposis
syndrome (FAP or aFAP), MUTYHassociated polyposis (MAP), Peutz-Jeghers
syndrome, Juvenile polyposis syndrome,
Serrated polyposis syndrome, Cowden syndrome or Li-Fraumeni syndrome, who
should be screened earlier. If an adenomatous polyp is found, complete removal
should be performed. Intervals for repeat
screening examinations depend on the presence and number of adenomatous polyps
found on the index colonoscopy, polyp size
and the presence of advanced adenomas
(high-grade dysplasia, sessile serrated histology, villous or tubulovillous histology).
If no adenomatous polyps are found at the
index colonoscopy, repeat examination is recommended in 10 years. Presence of 2 or
fewer low-risk adenomatous polyps should
prompt repeat examination in 5–10 years.
Three or more adenomatous polyps, or presence of advanced adenomas, should prompt a
repeat examination in 3years. Incomplete or
piecemeal polypectomy should prompt repeat
examination within 6months.
Patients with inammatory bowel disease
are recommended screening colonoscopy
8–10 years after the onset of symptoms.
Ongoing surveillance depends on disease
activity in addition to endoscopic ndings.
Individuals with a rst degree relative with a
colorectal cancer diagnosed at less than age
60 years should have their index examination at age 40, or 10 years earlier than the
age of earliest CRC diagnosis in that rstdegree relative. Individuals with a rstdegree relative with an advanced adenoma
should have their rst colonoscopy at either
age 50 or at the age of the family member
with the advanced adenoma, whichever is
earlier.
D. Even after appropriately timed screening
colonoscopy, interval adenocarcinomas can
occur in approximately 10.5% of patients.
The majority of these interval lesions occur in
the right colon. Theories as to the cause of
this phenomenon include a worse bowel
preparation in the right colon, biological differences in tumors of the right colon or an
63 Colonic Conditions: Adenomatous Polyps
485
increased proportion of at lesions in the
right colon that may have been missed at
screening colonoscopy. Meticulous inspection behind mucosal folds and behind the
ileocecal valve may help improve lesion
detection.
E. During colonoscopy, polypectomy of small
lesions (less than 3 mm in diameter) can
usually be achieved by use of a cold biopsy
forceps. The instrument is passed through
the working channel of the colonoscope and
the lesion excised, either in its entirety with
one pass or in “piecemeal” fashion. For this
purpose, the authors prefer using a “jumbo”
size forceps, as the jaws can accommodate
more tissue and help ensure a complete polypectomy. For larger polyps, biopsy forceps
may not allow for complete polypectomy. In
this situation, snare polypectomy may be
necessary to ensure complete polyp excision. This device is similarly passed via the
working channel of the endoscope. The
snare is opened and secured around the base
of the polyp. Complete closure of the device
amputates the lesion. Once complete, the
polyp can be grasped and withdrawn by
aide of a through- the- scope net or suctioned
through the colonoscope and captured in a
specimen trap. Submucosal injection can
also be utilized to aide in excision of the
polyp. An injectate such as normal saline,
glycerol, or hyaluronic acid is injected in
the submucosal plane beneath and around
the polyp, “lifting” the lesion off the muscularis propria. This can allow a snare to be
deployed around the lesion, and may also
minimize the possibility of transmural
injury to the bowel, particularly if cautery is
used. There is no consensus as to which
injectate provides the best results. Polyps
that do not lift appropriately during injection may indicate an invasive lesion, and
complete polypectomy may not be possible.
Prior attempts at polypectomy may also
cause scarring within the lesion, precluding
adequate lifting. For snare polypectomy, it
is often helpful to position the lesion at the
“5 o’clock” position on the screen, as this is
where the working channel port is. This
should allow proper positioning of the
snare.
F. Advances in exible endoscope technology
and equipment have provided the opportunity
to improve adenoma detection rates.
Advanced techniques are now available to
safely remove adenomas, both small and
large. In years past, patients discovered to
have large adenomas considered too large to
remove endoscopically were referred for surgical resection. Advanced endoscopic techniques, including endoscopic mucosal
resection (EMR) and endoscopic submucosal
dissection (ESD), have given endoscopists
the opportunity to offer patients a minimally
invasive approach to remove difcult colorectal polyps. While both techniques can be useful in avoiding major surgical resection for
pre-malignant lesions, there are some key differences between the two. EMR is widely
accepted for the resection of larger adenomatous polyps, however, larger lesions can be
difcult to remove completely
9
. ESD can be
used to improve completeness of resection
(R0) and thereby decrease recurrence rates. A
recent meta-analysis comparing EMR to ESD
utilized data from 6 trials and pooled evaluation of 1642 adenomatous polyps. ESD was
associated with higher en bloc resection and
lower local recurrence. The complication
rates were similar, however, ESD was more
time consuming.
G. Advanced trans-anal approaches are also
available for patients with large rectal polyps.
Transanal endoscopic microsurgery (TEMS)
and transanal minimally invasive surgery
(TAMIS) techniques have become more
widespread and can allow for safe removal of
accessible lesions. In a recent meta-analysis
comparing TEMS to conventional transanal
excision, TEMS was associated with a higher
rate of negative margins, less specimen fragmentation and lower recurrence rates, with no
difference in overall complications. Recently,
TAMIS has grown in popularity since its initial description in 2010 by Atallah etal. While
high quality data are still lacking, TAMIS has
486
S. A. Lee-Kong and P. R. Kiran
also shown promising results, comparable to
TEMS 14 in terms of achieving negative margins and minimizing polyp recurrence.
H. Surgical resection of the colon or rectum for
endoscopically unresectable adenomatous
polyps, outside of transanal approaches, usually requires partial colectomy. Patients
deemed appropriate surgical candidates are
offered abdominal surgery, which can be
done in traditional open fashion or by utilizing minimally invasive techniques. In general, traditional oncologic principles are
followed during the resection, as larger adenomatous polyps can harbor invasive cancer.
Some series report that for larger polyps
between 1.5cm and 3.5cm in diameter, the
risk of harboring an invasive cancer can range
from 19 to 43%. Ensuring adequate lymphadenectomy in this setting is important for cancer staging.
I. Cancer within a polyp: Endoscopic vs surgical
resection.
Adenomatous polyps with foci of invasive
cancer can be a management dilemma. The
risk of lymphatic spread is directly correlated
with the T-stage of the lesion. For pedunculated or sessile adenomatous polyps identied
at colonoscopy, endoscopic resection can be
entertained, if deemed appropriate by the
endoscopist. Patients with pedunculated adenomatous polyps with foci of invasive cancer
excised in 1 piece with clear margins, conrmed to be T1in depth and with favorable
histologic features (well or moderately differentiated, absent lymphovascular invasion) can
safely observed without resection. For sessile
lesions with the same above features, both
observation and radial resection can be considered appropriate treatment.
The Haggitt Classication system for
pedunculated polyps with foci of invasive cancer is useful to describe the level of invasion
into the submucosa. Haggitt level 1 lesions
have the component of adenocarcinoma limited to the head of the polyp. Level 2 lesions
have the adenocarcinoma extend to the neck
of the polyp. Level 3 lesions have cancer
extension to the stalk of the polyp, and in level
4 lesions extend beyond the stalk, but still limited to the submucosa. Haggitt levels 1–3 are
associated with a very low rate of lymph node
metastasis, and these lesions can be safely
managed with endoscopic polypectomy.
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Atallah S, Albert M, Larach S. Transanal minimally
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World J Gastroenterol. 2013;19:1953–61.
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Draganov PV, Chang MN, Alkhasawneh A, et al.
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Haggitt RC, Glotzbach RE, Soffer EE, Wruble
LD.Prognostic factors in colorectal carcinomas arising in adenomas: implications for lesions removed
by endoscopic polypectomy. Gastroenterology.
1985;89(2):328–36.
Keller DS, Haas EM. Transanal minimally inva-
sive surgery: State of the art. J Gastrointest Surg.
2016;20:463–9.
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63 Colonic Conditions: Adenomatous Polyps
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Colon Cancer Surgical Therapy
LameeseTabaja, YasirAkmal, andMaherA.Abbas
64
Refer toAlgorithm inFig. 64.1
A. The colon occupies portions of the retroperi-
toneal and intraperitoneal abdominal spaces,
in close proximity to multiple solid organs
and the small bowel. The ascending and
descending colon are retroperitoneal, while
the transverse colon is intraperitoneal. The
sigmoid colon ends where the taenia converge to form the rectum.
B. The entire right colon to the junction of the
middle and distal third of the transverse
colon are supplied by the right colic and the
ileo-colic arteries (Fig. 64.2), which are
branches of the superior mesenteric artery.
The middle colic artery supplies the majority
of the transverse colon. The arterial supply of
the distal transverse and left colon down to
the lower rectum are supplied by the left
colic and sigmoid arteries which are branches
of the inferior mesenteric artery. These
branches anastomose with the left branch of
the middle colic artery to form part of the
marginal artery of Drummond. The marginal
artery of Drummond and the arc of Riolan
provide the collateral blood circulation and
typically the blood supply of the transverse
L. Tabaja (*) · Y. Akmal · M. A. Abbas
Department of Colon and Rectal Surgery, Digestive
Disease Institute, Cleveland Clinic Abu Dhabi,
Abu Dhabi, United Arab Emirates
e-mail: TabajaL@clevelandclinicabudhabi.ae
colon is excellent, as long as the marginal
artery is not damaged. Variability in the arterial anastomoses occurs, which is an important point when performing a segmental
resection. The two most tenuous sites,
“watershed areas”, are the splenic exure
(Grifth’s point) and the distal descending
colon (Sudeck’s point). The venous and lymphatic drainage of the colon tends to parallel
the arterial supply (Figs.64.3 and 64.4). For
the right and left colon, the venous drainage
is through the superior and inferior mesenteric veins, respectively.
C. The extent of resection is based on the blood
supply that drains the tumor-bearing segment of the colon. It is recommended that
the proximal and distal margins are a minimum of 5cm. The mesentery of the affected
segment should be removed en bloc with the
major feeding vessel(s) and the dependent
lymphatic drainage. Any malignantappearing lymph nodes (LNs) outside the
boundaries of the resection should also be
removed if possible. Standard ligation of the
feeding vessel at the origin is recommended
by the American Society of Colon and Rectal
Surgeons (ASCRS). Furthermore, one large
study suggests a higher overall survival and
lower recurrence rate when high vascular
ligation is performed for Stages II and III
(i.e., Dukes B and C) colorectal tumors. A
minimum of 12 LNs should be identied and
evaluated from the resected colon cancer
© Springer Nature Switzerland AG 2020
S. R. Steele etal. (eds.), Clinical Decision Making in Colorectal Surgery,
https://doi.org/10.1007/978-3-319-65942-8_64
489