Добавил:
Sekretar
kiopkiopkiop18@yandex.ru
t.me/Prokururor I Вовсе не секретарь, но почту проверяю
Опубликованный материал нарушает ваши авторские права? Сообщите нам.
Вуз:
Предмет:
Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_636_Библиотеки_им_академика_М_И_Перельмана.pdf
25 Colon Cancer: Preoperative Evaluation andStaging
Table 25.1 TNM classication and AJCC 8th edition staging of colon cancer
Primary tumor (pT)
TX Primary tumor cannot be assessed
T0 No evidence of primary tumor
Tis Carcinoma in situ, intramucosal carcinoma (involvement of lamina propria
with no extension through muscularis mucosae)
T1 Tumor invades submucosa (through the muscularis mucosa but not into the
muscularis propria)
T2 Tumor invades muscularis propria
T3 Tumor invades through the muscularis propria into the pericolorectal tissues
T4
T4a Tumor invades through the visceral peritoneum (including gross perforation
of the bowel through tumor and continuous invasion of tumor through areas
of inammation to the surface of the visceral peritoneum)
T4b Tumor directly invades or adheres to other adjacent organs or structures
Regional lymph nodes (pN)
NX Regional lymph nodes cannot be assessed
N0 No regional lymph node metastasis
N1 Metastasis in 1–3 regional lymph nodes
N1a Metastasis in 1 regional lymph node
N1b Metastasis in 2–3 regional lymph nodes
N1c No regional lymph nodes are positive but there are tumor deposits in the
subserosa, mesentery, or nonperitonealized pericolic or perirectal/mesorectal
tissues
N2 Metastasis in 4 or more regional lymph nodes
N2a Metastasis in 4–6 regional lymph nodes
N2b Metastasis in 7 or more regional lymph nodes
Distant metastasis (pM)
M0 No distant metastasis by imaging; no evidence of tumor in other sites or
organs (this category is not assigned by pathologists)
M1 Distant metastasis
M1a Metastasis conned to 1 organ or site without peritoneal metastasis
M1b Metastasis to 2 or more sites or organs is identied without peritoneal
metastasis
M1c Metastasis to the peritoneal surface is identied alone or with other site or
organ metastases
Stage grouping
Stage 0 Tis N0 M0
Stage I T1–T2 N0 M0
Stage IIA T3 N0 M0
Stage IIB T4a N0 M0
Stage IIC T4b N0 M0
Stage IIIA T1–T2 N1/N1c M0
T1 N2a M0
Stage IIIB T3–T4a N1/N1c M0
T2–T3 N2a M0
T1–T2 N2b M0
Stage IIIC T4a N2a M0
T3–T4a N2b M0
T4b N1–N2 M0
Stage IVA Any T Any N M1a
Stage IVB Any T Any N M1b
Stage IVC Any T Any N M1c
345
346
C. B. Aarons and N. N. Mahmoud
• Other histologic criteria that are associated
with prognosis:
– Tumor grade: low grade (well- and moder-
ately differentiated) versus high grade
(poorly differentiated and undifferenti-
ated)
– Tumor (“satellite”) deposits
– Lymphovascular invasion
– Perineural invasion
– Mucinous or signet ring cell morphology
– Margin status (distal, proximal, and
radial)
• Non-peritonealized resection margins
for all cases of neoplasia resection
should be inked to allow for assessment
of radial margin status. This is best performed on the fresh specimen.
Lymph Node Evaluation
• Other than radial margin status, lymph node
status is the most important prognostic factor
following resection of colon cancer.
• The identication of at least 12 lymph nodes
has been suggested as a key quality indicator
in the resection of colon cancers.
– While there are patient-related factors that
inuence lymph node yield, the completeness of mesenteric resection and the interest of the pathologist in obtaining the
maximal number for nodes for examination
are also paramount. Numerous studies have
shown that increasing the number of lymph
nodes examined is associated with
improved survival in stage II and stage III
patients.
– Tumor deposits that are found in the peri-
colonic fat that do not show any evidence
of residual lymph node are not counted as
lymph nodes replaced by tumor and are
designated as N1c. The number of these
nodules should be reported as they confer a
poor prognosis.
• Lymph node ultraprocessing (microsectioning, immunohistochemical analysis, or
RT-PCR) has been demonstrated to increase
the number of nodes found to have tumor.
However, there is no denitive evidence that
treatment of patients with occult nodal
metastases with chemotherapy improves
survival.
• Many studies of sentinel lymph node mapping
(injection of vital dye around the tumor at the
time of operation as a method of identifying
lymph nodes theoretically at greatest risk for
metastases) have been fraught with bias. To
date, sentinel node mapping for colorectal
cancer has not been demonstrated to be
effective.
Lynch Syndrome Phenotype
• Assessment for Lynch tumor phenotype via
immunohistochemistry (IHC) looking for
expression of mismatch repair (MMR) proteins (MLH1, MSH2, MSH6, PMS2) should be
performed. Some institutions perform this
selectively, based on family history, or routinely on all colon cancer specimens.
• In general, patients with absence of MMR on
IHC should be considered for referral to a
genetic counselor and germline mutational
analysis.
• The exception to the above recommendation
is when MLH1 is absent on IHC.In addition
to Lynch syndrome, absence of MLH1 on IHC
can be due to mutation of BRAF. This is common in older female patients.
– Prior to germline mutational analysis for
Lynch, the tumor should undergo BRAF
analysis.
– If BRAF is mutated, then a sporadic muta-
tion in MLH1 is 96% likely. Lynch is thus
unlikely and, in most cases, the patient can
be considered to have a sporadic cancer,
and genetic testing will cease.
– If BRAF is normal, then Lynch is likely,
and genetic counseling and testing should
be considered.
– In some institutions, reex BRAF testing is
performed on any tumor specimen with
absent MLH1 on IHC.
25 Colon Cancer: Preoperative Evaluation andStaging
347
• Microsatellite instability (MSI) in the tumor is
another indicator of DNA repair defects
caused by defective mismatch repair proteins.
– It is typically assessed by PCR amplica-
tion of repeated single-nucleotide units of
DNA, or microsatellites, in tumor tissue.
– Tumors are characterized as MSI-high
(MSI-H) or MSI-low (MSI-L) based on the
number of microsatellite sequences that
appear.
• If the tumor has two or more mutated
sequences, it is termed MSI-H, while if
only one sequence is mutated, it is classied as MSI-L.Finally, if no mutation
is present, then the tumor is microsatellite stable (MSS).
• Patients with MSI-H tumors should be
considered for genetic counseling and
germline mutational analysis to look for
Lynch syndrome.
• IHC for MMR has replaced MSI testing
in most institutions because of the
reduced cost and the fact that it is a
direct measurement of protein product.
The Surgical Management of Colon Cancer
Matthew G. Mutch
26
Key Concepts
• Complete clinical staging for colon cancer
includes a total colon exam, computed tomography of the chest, abdomen, and pelvis, and
measurement of serum CEA level.
• The principles of an oncologic resection
include a total mesocolic resection, ligation of
the primary vessel at its origin, a wide mesenteric resection with >12 lymph nodes examined, and at least a 5cm resection margin.
• There is no difference in cancer-related outcomes for open and laparoscopic resections.
• Anastomotic assessment for left-sided anastomosis is associated with a decreased leak rate.
• Surgical resection is the most effective therapy for patients who present with obstruction
colon cancers.
• Endoscopic stenting of an obstructing colon
cancer is an effective bridge to surgery within
72h.
• Perforated cancers should be treated with an
oncologic resection.
• First-line therapy for patients with metastatic
colon cancer and an asymptomatic primary
tumor is chemotherapy.
M. G. Mutch (*)
Section of Colon and Rectal Surgery, Department
of Surgery, Washington University School
of Medicine, St. Louis, MO, USA
e-mail: mutchm@wudosis.wustl.edu
Preoperative Preparation
Physiologic Assessment
• A variety of scoring systems are available for
stratifying a patient’s risk of perioperative
morbidity and mortality after undergoing
major digestive system surgery. Each scoring
system differs in the included parameters and
the outcomes that they measure.
– The most widely utilized scoring system is
the American Society of Anesthesiologists
(ASA) Score, but it only provides
assessment of an anesthesia complication
for a given patient’s physiologic status.
– In contrast, the POSSUM and modied
Portsmouth-POSSUM scoring systems
provide an assessment of the risk of postoperative mortality and morbidity.
◦ In an effort to improve the performance
prediction of patients undergoing
colorectal resections, a colorectalspecic POSSUM (CR-POSSUM)
score was developed.
– The American College of Surgeons devel-
oped a surgical risk calculator using data
from NSQIP to provide patient-specic
postoperative risks of various complications. The NSQIP risk calculator has been
shown to underestimate the risk of complications for colorectal resections, and more
© ASCRS (American Society of Colon and Rectal Surgeons) 2019
S. R. Steele et al. (eds.), The ASCRS Manual of Colon and Rectal Surgery,
https://doi.org/10.1007/978-3-030-01165-9_26
349
350
M. G. Mutch
surgeon- and patient-specic data are
needed. However, it remains a useful tool
to preoperatively assess morbidity and
mortality risk. The risk calculator is available at http://riskcalculator.facs.org.
Tumor Localization
• Accurate tumor localization is a critical component of the preoperative assessment of the
patient and operative planning. Intraoperative
tumor localization can be challenging from
several standpoints such as small or early
tumor, obese patient, adhesions, laparoscopy,
or inadequate tattooing.
– The utilization of intraluminal anatomic
markings for tumor localization is inaccurate 10–15% of the time and may be higher
if cecal and rectal tumors are excluded. In
other words, the colonoscopy will not
accurately locate the tumor one out of
seven times.
– Localization with endoscopic tattooing
provides the most accurate method for
localization. The tattoo should be placed
distal to the lesion and in three separate
areas around the circumference of the
lumen (Fig. 26.1). A single injection into
the mesenteric border or sprayed into the
peritoneal cavity may be difcult to
identify.
– Alternatively, endoscopic placement of
metal clips at the site of the tumor with
immediate plain radiograph (or CT) will
localize the tumor with a high degree of
accuracy.
– The ultimate fallback to identify a lesion is
intraoperative colonoscopy, ideally using
carbon dioxide as the insufation gas to
limit bowel dilatation.
– Patients who present with endoscopically
obstructing lesions can be effectively evaluated with CT colonography to complete
their total colon exam prior to surgery. CT
colonography has replaced contrast enema
studies in many situations because of
improved accuracy in detecting synchronous lesions and often provides better
tumor localization.
Surgical Technique
Extent of Resection
• The National Comprehensive Cancer Network
provides the recommended principles of surgical resection for colon cancer, which include
obtaining an adequate proximal margin, distal
margin, and lymphadenectomy.
• Colon cancers tend to grow circumferentially
around the lumen of the colon and extend out
radially and, to a lesser degree, longitudinally
along the bowel. Therefore, a 5cm proximal
or distal margin has always been recommended. This is important to remove all
tumor-bearing mucosa but also to resect all
lymph nodes with potential to drain tumor
cells.
• In order to obtain an adequate lymphadenectomy, the named feeding vessel to the resected
segment of the colon should be taken at its origin. The goal is to clear all regional lymph
nodes and provide a minimum of 12 lymph
nodes for pathologic evaluation.
Mesocolic Resection
• Just as the mesorectum is enveloped in a fascia, the mesocolon also has a visceral fascial Fig. 26.1 Tattoo localization of a sigmoid colon cancer
26 The Surgical Management of Colon Cancer
351
plane that separates it for the retroperitoneum
(parietal fascia). A serosal surface on the
bowel and mesentery excludes the anterior
aspect of the mesentery from the perineal
cavity.
• Complete mesocolic excision (CME), as popularized by Hohenberger et al., is the sharp
dissection of the visceral fascia from the parietal fascia of the retroperitoneum and central
ligation of the primary vasculature.
Right Colectomy
• Tumors located anywhere from the cecum to
the proximal transverse colon can safely be
treated with a right colectomy. The basic
tenets of resection of a right-sided tumor
include full abdominal exploration, full mobilization of the right colon, and hepatic exure
with a mesenteric resection including ligation
of the ileocolic and right branch of the middle
colic vessels at their origin. The resection can
be performed safely and effectively via either
an open or laparoscopic approach. Data
regarding laparoscopy and colorectal cancer is
presented in detail below.
• The initial approach to mobilization can vary
based on the anatomy of the tumor and the
preference of the surgeon. It is often helpful to
completely mobilize the colon and mesentery
away from the site of the tumor before embarking on dissection in the area of the tumor,
especially when the cancer is locally advanced
and invasive into the retroperitoneum.
• All of the surgical approaches contain the
same steps. They are typically named according to the initial approach to mobilization.
Open Approach
• The peritoneal cavity can be accessed with a
midline or right-sided transverse or oblique
incision.
• Once the abdomen is opened and explored and
the tumor is located, the wound should be protected with a wound protector.
• The colon and its mesentery are separated
from the retroperitoneum, returning the colon
to its embryologic position in the midline.
Care is taken to preserve retroperitoneal structures such as the duodenum, pancreas, and ureter. The hepatic exure is mobilized. The
omentum is divided in the midline and the
right side of the omentum resected en bloc
with the colon. With the colon completely
mobilized, the vascular pedicles can be ligated.
• The “approaches” are named for their initial
maneuvers. However, regardless of the named
technique, the steps are the same, and only
their order is different.
Lateral-to-Medial Approach
• The surgeon stands on the patient’s left side
and the rst assistant on the patient’s right
side.
• The right colon is grasped, and the peritoneum
is incised just anterior to the white line of
Toldt from the cecum to the hepatic exure.
This allows access to the avascular plane
between the visceral and parietal planes of the
colon and retroperitoneum. It is important not
to violate the mesenteric side of this plane in
order to ensure a total mesocolic resection.
• Under tension, the right colon is separated
sharply from the retroperitoneum. The duodenum should be identied and reected into the
retroperitoneum. The cecum is then mobilized
off the retroperitoneum, and the posterior
attachments of the small bowel mesentery are
divided all the way up to the duodenum. This
provides the mobility of the small bowel for
the anastomosis.
• With the duodenum safely reected posteriorly, the hepatic exure can be mobilized. The
surgeon’s left hand is placed under the colon
and its mesentery and brought out laterally to
expose the superior attachments along the
inferior edge of the liver.
• Eventually, the lesser sac is entered and the
lesser omentum is divided. Care must be taken
so the plane between the omentum and the
transverse colon mesentery is separated, and
dissection into the transverse colon is avoided.
These two planes are typically fused up to the
midline, and beyond this point, the proper
lesser sac is entered.
352
• After the right colon and hepatic exure are
completely mobilized, the cecum is put on
stretch, and the ileocolic pedicle can easily be
identied. Since the right colon and its mesentery have been mobilized, there should be bare
areas on the cephalad and caudad aspects of
the ileocolic pedicle. The peritoneum is
incised along the lines of resection for both
bare areas allowing isolation of the pedicle so
it can be ligated at its origin on the superior
mesenteric vessels.
• The terminal ileal mesentery is divided so that
an adequate amount of ileal mesentery is
included with the specimen, depending on the
location of the tumor.
• The right branch of the middle colic vessels is
identied by elevating the transverse colon
mesentery. The pedicle should become evident either by bowstringing it under tension or
there should be another bare area where the
omentum has been dissected free during the
exposure of the lesser sac. The peritoneum
should be incised from the distal site of transection of the colon to the base of the pedicle
and across the pedicle to the cut edge of the
right colon mesentery. The pedicle can then be
ligated at its origin.
M. G. Mutch
Fig. 26.2 Exposure of the posterior aspect of the small
bowel mesentery for the posterior approach to the right
colon
Posterior (Inferior-to-Superior) Approach
• The principal difference between this approach
and the lateral-to-medial approach is that the
initial step in the operation is to mobilize the
root of the ileal mesentery rst to the level of
the duodenum.
• The small bowel is eviscerated and reected
toward the right upper quadrant to expose the
posterior aspect of the small bowel mesentery
from the ligament of Treitz to the cecum
(Fig.26.2).
• The peritoneum is incised along the root of the
ileal mesentery to the midline, and the plane
between the mesentery and the retroperitoneum is entered (Fig.26.3). The duodenum is
readily identied and reected into the
retroperitoneum.
• The right colon mesentery is elevated off the
retroperitoneum out beyond the ascending
Fig. 26.3 Entry into the retroperitoneum from the posterior approach to a right colectomy
colon laterally and the transverse colon
superiorly.
• The further this dissection can be performed
from a medial-to-lateral direction beyond the
transverse colon, hepatic exure, and ascending colon, the easier the lateral dissection
becomes as all that remains are the lateral
peritoneal and lesser omental attachments. At
26 The Surgical Management of Colon Cancer
353
this point, starting at the level of the cecum,
the surgeon, while standing on the patient’s
left side, places their left hand under the right
colon mesentery and lateral to the colon to
expose the lateral peritoneal attachments.
These are then divided heading up toward the
hepatic exure.
• If the dissection is continuing easily, the lesser
omentum is separated from the transverse
colon mesentery in order to enter the lesser
sac. If this plane is difcult to develop, the distal site of transection is identied, and the
lesser sac can be entered at this point. This
begins by dividing the greater omentum to the
level of the colon, and the lesser omentum is
bluntly separated from the colon and its mesentery to enter the lesser sac. Once the lesser
sac is entered, this plane is developed toward
the hepatic exure. Eventually, the posterior
retroperitoneal dissection plane is entered.
With the duodenum free, the remaining attachments along the inferior liver can be safely
divided. The right colon and hepatic exure
are completely mobilized so the vascular pedicles can be ligated, and the mesentery can be
resected as described above.
Superior to Inferior Approach
• The principal difference between this approach
and the lateral-to-medial and inferior-tosuperior approaches is that the initial step in
the operation is to divide the omentum over
the transverse mesocolon and mobilize hepatic
exure rst.
• The superior approach is useful for locally
advanced tumors of the cecum and proximal
ascending colon with possible retroperitoneal
invasion because it allows for complete mobilization of the colon and mesentery before
addressing the site of the tumor.
• The dissection begins at the distal site of transection of the transverse colon. This is accomplished by elevating the transverse colon to
expose its inferior aspect of the mesentery so
the right branch of the middle colon vessels
can be identied. It is the rst pedicle medial
to the bare area of the duodenum and should
bowstring under the tension of the elevating
the transverse colon. The greater omentum is
divided up to the transverse colon, and the
lesser omentum is separated from the colon
and mesentery to enter the lesser sac.
• As this plane is developed toward the hepatic
exure, the lesser omentum is divided. The
stomach superiorly and duodenum posteriorly
should be identied and separated from the
colon mesentery.
• Once the lesser omentum or hepatic attachments to the colon are divided beyond the
hepatic exure, the hepatic exure can be elevated under tension to develop the retroperitoneal plane, identify and free the duodenum,
and divide the lateral peritoneal attachments
of the right colon.
• With the peritoneal attachments divided, the
remaining colon is mobilized in the same
manner as described in the lateral approach.
Medial-to-Lateral Approach
• This approach is helpful when the tumor is
invasive into the retroperitoneum over the
kidney and/or duodenum or there is question
of ureteral involvement.
• The dissection begins at the root of the ileocolic mesentery from the medial aspect. The
ileocolic vessels are isolated and divided and
the right colon mesentery dissected away from
the duodenum and pancreas, if they are not
involved with tumor.
• The mobilization continues inferiorly lifting
the ileal mesentery away from the retroperitoneum, taking care to preserve the ureter and
gonadal vessels.
• The ileal mesentery and terminal ileum can be
divided at this point.
• The omentum is divided over the transverse
mesocolon, allowing control of the mesocolon
from both superior and inferior aspects.
• The right branch of the middle colic vessels is
divided. The remainder of the transverse
mesocolon is divided. The transverse colon is
divided.
• This leaves the lateral attachments of the
colon. The surgeon can then assess the degree
of invasion of the tumor into the retroperitoneum and make a decision whether en bloc
354
resection of any adjacent organs is required.
The ureter should be free from a medial
aspect, so if retroperitoneal en bloc excision is
required, there should be little risk of ureteral
injury.
Anastomosis
• Ileocolic anastomosis can be accomplished
via handsewn or stapled techniques.
• Handsewn anastomosis may be performed in
end-to-end or side-to-side fashion and can be
created using a single or double layer of
sutures. However, an end-to-end anastomosis
is often difcult given the signicant size discrepancies between the lumens of the small
bowel and colon.
• Stapled anastomoses are most commonly performed in a side to side fashion but can also be
performed in a side to end conguration as
well. The traditional side to side, stapled anastomosis is created by individually dividing the
proximal (Fig. 26.4) and distal limbs
(Fig.26.5) of the bowel with a stapler.
• The anti-mesenteric corner of each staple line
is then excised, and the forks of the stapler are
placed into the lumen of each limb of the
intestine. The stapler is reassembled and red
with the bowel in an antiperistaltic and antimesenteric fashion (Fig.26.6).
• The resulting common enterotomy is reapproximated so the longitudinal staple lines are
offset, which prevents the intersection of more
than two staple lines (Fig.26.7).
• The common enterotomy can be closed with
suture or staples (Figs.26.8 and 26.9).
• An alternative method for creating the side to
side anastomosis is not to divide the proximal
and distal bowel. Enterotomies are made on
the anti-mesenteric side at the chosen site of
transection proximally and distally. The forks
of the staple are then passed through each
enterotomy where they are reassembled and
red in an anti-mesenteric position, as above.
The common enterotomy is closed by ring
the linear cutting stapler again, across the
M. G. Mutch
Fig. 26.4 Division of the terminal ileum. (Courtesy of
Howard Ross, MD)
Fig. 26.5 Division of the transverse colon. (Courtesy of
Howard Ross, MD)
26 The Surgical Management of Colon Cancer
355
Fig. 26.6 Firing of the linear stapler for a side to side
stapled anastomosis. (Courtesy of Howard Ross, MD)
Fig. 26.8 Closing the common enterotomy for a side to
side anastomosis. (Courtesy of Howard Ross, MD)
Fig. 26.9 Complete side to side ileocolic anastomosis.
(Courtesy of Howard Ross, MD)
Fig. 26.7 Closing the common enterotomy by offsetting
the longitudinal staple line. (Courtesy of Howard Ross, MD)