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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_636_Библиотеки_им_академика_М_И_Перельмана.pdf
398
M. H. Whiteford
Germany). TEM involves a 4×12 (or 20) cm
cylindrical metal reusable operating rectoscope mounted to the operating table. The rectoscope has a sealed faceplate with multiple
access ports that permit simultaneous pneumodistention of the rectum along with passage of a stereoscopic camera and modied
laparoscopic instruments into the rectum.
Stable pneumorectum is maintained with a
dedicated TEM suction-CO2 insufation
pump. TEM instruments could now remove
larger lesions as well as lesions up to the rectosigmoid junction (~17 cm from the anal
verge). A similar reusable rigid proctoscopic
transanal endoscopic operation (TEO®) system is also commercially available (Karl
Storz, GmbH, Tuttlingen, Germany).
• In 2010, Atallah rst described the use of a
commercially available single-port laparoscopic platform placed transanally in conjunction with standard laparoscopic
instruments and insufators to perform transanal surgery. This technique has been coined
transanal minimally invasive surgery
(TAMIS). Due to the similarities of the techniques and clinical results, TEM, TEO, and
TAMIS are collectively termed transanal
endoscopic surgery (TES).
Techniques
Technique forConventional Transanal
Excision
General anesthesia is the most common mode
of anesthesia, but spinal anesthesia is an
acceptable option.
• Patient positioning is chosen such that the target pathology is placed dependently: lithotomy position for posterior lesions and prone
jackknife for anterior and lateral lesions.
• Exposure is obtained via the surgeon’s preferred method of self-retaining anal retractor,
lighted anoscope, operating proctoscope, and
®
Lone Star
retractor (Cooper Surgical, Inc.,
Trumbull, CT). A headlight provides ideal
illumination in the tightly conned operating
eld.
• Electrocautery is then utilized to demarcate a
5–10 mm margin around the lesion. Stay
sutures may be placed on the normal rectal
wall away from the tumor for retraction and
improved visibility. Dissection progresses distally, laterally, and then proximally with sharp
or electrocautery dissection.
• Depth of dissection is in the submucosal plane
for benign-appearing lesions or to avoid
sphincter injury and full-thickness dissection
for biopsy-proven malignant lesions or lesions
with gross features of malignancy.
• Most authors advocate for primary transverse
closure as longitudinal closure is thought to
predispose to stricture. At times, there may be
too much tension to close the defect. These
can then either be partially closed or left open
to heal by secondary intention if the defect is
extraperitoneal (Fig.29.1).
• Preoperative examination should include digital rectal examination with proctoscopy to
determine and document the longitudinal and
circumferential location, extent of the lesion,
and its proximity to the sphincter. Repeat or
deeper biopsy can also be performed if colonoscopic biopsy was nondiagnostic. When
concern for malignancy exists, then additional
imaging studies such as endoscopic ultrasound, MRI, and CT scan may be considered.
• The patient usually receives a full mechanical
bowel prep and perioperative antibiotics.
Fig. 29.1 Open wound following local excision
29 Local Excision ofRectal Neoplasia
Technique forTEM andTEO
• Bowel preparation, anesthetic choice, and
positioning are the same as transanal
excision.
• Gentle digital dilation is performed to accommodate the 4-cm-diameter proctoscope, which
is then inserted and attached to the table
mount. Both 12 and 20cm lengths are available. The faceplate is attached and tubing connected to the suction insufator unit.
Pneumorectum is established and the proctoscope adjusted to view the target lesion
through the stereoscopic microscope or the
laparoscopic video monitor.
• Three 5–9mm instrument ports are available
for use of the modied angled TEM laparoscopic instruments. Needle tip electrocautery
is utilized to demarcate a 5–10 mm margin
around the lesion.
• Submucosal or full-thickness dissection is
then initiated. This is most easily started in
the distal right corner of the lesion with progression toward the proximal left corner.
Partial en bloc resection of the mesorectum
has also been described for deeper malignant
lesions.
• Continuous suction functions to clear the cautery smoke during the procedure. The integrated suction-insufation unit prevents loss
of pneumorectum from the suctioning.
• Following specimen removal, the defect is
closed transversely using a running absorbable suture. A metal clip is locked at each end
of the suture in lieu of intracorporeal knot
tying. With the increased proximal reach of
TEM, intraperitoneal entry occasionally
occurs and, in experienced hands, can safely
be closed via the TEM instrumentation.
• TEM does suffer from technical limitations of
the rigid proctoscope causing signicant
instrument conict and has a longer learning
curve for both technique and instrument troubleshooting than compared to other transanal
techniques (Figs.29.2, 29.3, and 29.4).
399
Fig. 29.2 Transanal endoscopic microsurgery
Fig. 29.3 Margin around sessile polyp demarcated with
monopolar cautery during TEM. (Courtesy Mark
Whiteford, MD)
Fig. 29.4 Full-thickness depth of excision during TEM.
(Courtesy Mark Whiteford, MD)
400
M. H. Whiteford
Technique forTAMIS
• TAMIS is a modication of TEM whereby the
reusable rigid 4-cm-diameter operating proctoscope is replaced by a exible, disposable
single-port laparoscopic platform. Standard
laparoscopic insufators, camera, instruments, and vessel-sealing devices are also
utilized.
• Patient selection and preparation are similar to
TAE and TEM.The shorter length and exible
platform of the TAMIS technique more easily
permit operating on the nondependent (downward) wall of the rectum. For this reason, the
majority of cases can be done in the lithotomy
position.
• Dissection is performed in a similar fashion as
with TEM.
• Laparoscopic suctioning must be done judiciously as not to lose pneumorectum and
exposure. A more liberal use of laparoscopic
vessel-sealing devices provides improved
hemostasis over that of monopolar cautery,
thereby reducing the need for suctioning.
• Defect closure techniques vary among authors
and include the use of different laparoscopic
suturing devices or barbed sutures.
• Intraperitoneal entry during TAMIS is more
likely to require laparoscopic assistance for
defect closure due to loss of the rectum and
visualization of the defect via the transanal
device.
• Since the TAMIS devices rely on radial xation to the top of the sphincter complex, lowlying rectal polyps become partially obscured
by the transanal device and require a hybrid
TAMIS and TAE resection technique. This
involves dissection of the proximal portion of
the lesion utilizing the TAMIS technique and
then removal of the TAMIS device followed
by the conventional TAE technique to complete the distal dissection and defect closure.
• All forms of transanal excision techniques
have limitations such as the potential for
incomplete resection or the requirement for
conversion to an alternate technique, such as
staged transanal procedures or need for an
abdominal approach to complete the resection
or defect closure. These events are more likely
when the tumor is too bulky to permit adequate working space, the proximal extent of
tumor cannot be visualized around a fold or
sigmoid bend, uncontrolled bleeding is
encountered, or there is an inadequate bowel
preparation.
• Transcoccygeal (Kraske) and transsphincteric
(York-Mason) approaches to locally excise
rectal neoplasia have largely been supplanted
by these purely transanal techniques.
Transanal Excision ofBenign
Rectal Polyps
• The ideal indication for transanal excision is
for the complete removal of benign lesions in
the rectum. Radical surgery, in the form of
proctectomy, which includes a complete
regional lymphadenectomy, provides no clinical benet over transanal excision in the setting of benign disease yet subjects the patient
to considerable perioperative morbidity and
signicant long-term risk of urinary, sexual,
and defecatory dysfunction.
• Local excision also has the advantage of acting as a “total biopsy” to assess for completeness of resection and presence of otherwise
occult cancer.
• Most rectal polyps are detected on screening
colonoscopy in asymptomatic patients. While
most small polyps are readily removed using
colonoscopic polypectomy, larger polyps that
would generally require piecemeal snare polypectomy are better served with transanal
excision which provides a higher chance of
complete polyp removal and a resultant lower
chance of polyp recurrence. Endoscopists
should thus be encouraged to avoid piecemeal
endoscopic resection of large rectal polyps
and instead refer them for consideration of en
bloc transanal excision.
• Larger rectal polyps, particularly villous adenomas, have a higher incidence of harboring
an occult cancer despite benign appearance
and biopsies. For this reason preoperative
assessment with endoscopic ultrasound is
29 Local Excision ofRectal Neoplasia
401
reasonable to further assess tumor and nodal
staging.
• Benign polyps can be removed using either a
partial-thickness (submucosal plane) or fullthickness technique (deep to muscularis propria). Partial-thickness dissection is facilitated
through the use of submucosal injection of
saline with or without epinephrine to help raise
the polyp and mucosa off the muscularis propria. A non-lifting sign is worrisome for invasive cancer and is an indication for consideration
of conversion to full-thickness excision for
complete histologic assessment. A true submucosal dissection does not require defect closure
provided there is no concern for full-thickness
intraperitoneal entry. Alternatively, the mucosa
is usually fairly mobile, and most defects can
be closed primarily.
• It should be noted that the submucosal plane is
much more likely to be scarred or obliterated
if the patient has undergone prior piecemeal
hot snare polypectomy or multiple attempts at
endoscopic excision. Full-thickness excision
may be required in this situation if the layers
of the rectal wall are fused by scar. This is just
another reason why piecemeal endoscopic
resection should be avoided for large rectal
polyps.
ingly suboptimal. Heterogeneous study
populations (mixing benign and malignant
pathology of various T stages), lack of appropriate time-to-event analysis, retrospective
study design, and selection bias plague much
of the published literature on the topic. It
should also be remembered that, as of this
writing, there have been no prospective, randomized comparisons of local excision techniques. It remains unclear whether any
surgical technique is truly superior to any
other, especially for lesions in the distal
rectum.
• While there are no guidelines that mandate a
recommended follow-up strategy following
TES for benign rectal polyps, many surgeons
performed endoscopy every 6–12months for
2–3years. Routine endoscopic ultrasound and
imaging are not recommended for benign
disease.
• Some newer advanced colonoscopic techniques, endoscopic mucosal resection (EMR)
and endoscopic submucosal dissection (ESD),
are being utilized for excision of benign
colorectal polyps. EMR is usually a piecemeal
resection, whereas ESD attempts a single en
bloc resection. These techniques are primarily
utilized in Asia with limited North American
and European experience.
Results
• Local excision with TAE, TEM, and TAMIS is
typically performed in the outpatient setting.
The goal of transanal excision is complete en
bloc removal of the target pathology with minimal morbidity and mortality. Numerous case
series and several comparison trials demonstrate a low perioperative complication rate
(10–17%) and a less than 1% mortality rate
following TAE and TEM.
• There are some nonrandomized studies that
suggest that the quality of TEM excision,
however, is better than TAE with the incidence
of specimen fragmentation, positive margins,
and local recurrence favoring TEM.
• However, the quality of the studies of outcomes following local excision is distress-
TES forRectal Cancer
• Curative surgery for rectal cancer aims to
maximize the oncologic clearance of the primary tumor as well as the mesorectal lymph
nodes. Proctectomy is the accepted gold standard surgical procedure for rectal cancer with
5-year local recurrence rates in the 5–10%
range. The procedure, however, comes with
signicant risk of perioperative complications; long-term defecatory, urinary, and
sexual dysfunction; and frequent need for
temporary or permanent ostomies.
• Local excision has long been an appealing
option for rectal cancer because of its low risk
of morbidity and mortality, relative paucity of
long-term functional sequelae, and the
402
M. H. Whiteford
potential for curative treatment of disease limited to the bowel wall. The ideal candidate for
local excision is a patient who has no lymph
node metastasis and has a primary tumor
which can be excised with negative margins.
In such a situation, local excision should be
curative. The great controversy, however, is
that our ability to predict lymph node metastases is disappointingly poor and local recurrence following transanal excision remains
much higher than with radical surgery.
• Local excision can be utilized as a tool to gain
additional information regarding tumor biology and risk of lymph node metastasis. This
may help guide clinical judgment in deciding
whether or not a patient can be spared radical
surgery. It is wise to clarify this concept with
the patient preoperatively. The local excision
will be utilized as a “total biopsy” to help
guide treatment recommendations.
• If this total biopsy reveals high-risk histologic
features, then a recommendation for subsequent radical surgery will be made. However,
if no high-risk features are identied and the
priorities and values of a patient are such that
they accept a potentially higher risk of local
recurrence than with proctectomy, local excision may be considered acceptable treatment.
Local excision remains most appealing in
patients who are unt or unwilling to undergo
radical surgery.
• Lymph node status dramatically effects patient
prognosis as well as our treatment decisions
and recommendations. Current efforts to predict lymph node status consist of identifying
high-risk histopathologic features from biopsy
specimens. This is complemented with
selected imaging modalities. When considering patients for local excision, it is imperative
to choose those with the lowest risk of harboring locoregional metastatic disease.
Predicting Risk ofLymph Node
Metastasis
• Prediction of lymph node metastasis for rectal
cancer is an imprecise science. No single his-
tologic feature can solely predict risk of lymph
node metastasis nor is there any currently
available genetic or molecular marker that is
predictive.
• Through a combination of histopathologic
characteristics and imaging modalities, the
surgeon and the patient try to roughly generate
a risk-benet calculation to guide clinical
strategies related to local excision versus radical surgery.
• Colonoscopic biopsies alone sample but a
small portion of the tumor, whereas an excisional full-thickness biopsy allows the fullest
examination of the tumor histology, death of
invasion, and margin status. Unfavorable histologic features are not only independently predictive of lymph node metastasis, but multiple
unfavorable features also have an additive risk.
Depth ofInvasion
• Depth of tumor invasion into the wall of the
bowel has traditionally been one of the best
predictors of lymph node metastasis and is an
assessable variable in nearly all complete
excisions.
– T1 tumors, which are limited to the submu-
cosa, are associated with a 10–15% incidence of occult lymph node metastases
detected at the time of radical surgery.
– T2 tumors, which invade into but not
through the muscularis propria, are associated with a 20–26% risk of lymph node
metastasis.
• Kikuchi further identied the importance of
depth of submucosal invasion on lymph node
metastases and local recurrence among T1
cancers. They analyzed a large series of
patients subdivided by the cancer depth of
invasion into the upper, middle, and lower
thirds of the submucosa (SM1, SM2, SM3)
and demonstrated an incremental increase in
risk of lymph node metastasis or local recurrences with deeper depth of invasion. Tumors
invading to the SM3 level were shown to have
a similar risk of lymph node metastasis and
local recurrence as T2 cancers.
29 Local Excision ofRectal Neoplasia
Table 29.1 Local recurrence rates (percentage) at 36months following TEM excision of rectal cancer
Maximum tumor diameter (cm)
Depth of invasion
pT1 sm1 No 3.0 3.6 4.4 5.4 6.6 8.1
pT1 sm2–3 No 10.5 12.7 15.3 18.5 22.1 26.4
pT2 No 9.8 11.9 14.3 17.3 20.7 24.7
pT3 No 19.7 23.6 28.0 33.2 39.0 45.4
With permission from Bach SP, Hill J, Monson JR, Simson JN, Lane L, Merrie A, Warren B, Mortensen NJ.Transanal
Endoscopic Microsurgery (TEM) Collaboration. A predictive model for local recurrence after transanal endoscopic
microsurgery for rectal cancer. Br J Surg. 2009;96(3):280–90. Copyright © 2009 John Wiley & Sons, Inc
pT pathological tumor stage, sm1 and sm2–3 Kikuchi submucosal stage
Lymphatic invasion
Yes 5.2 6.4 7.7 9.4 11.4 13.7
Yes 17.8 21.4 25.5 30.3 35.7 41.8
Yes 16.7 20.0 23.9 28.5 33.7 39.5
Yes 32.2 37.9 44.1 51.0 58.3 65.7
≤1
1.1–2 2.1–3 3.1–4 4.1–5
403
≥5.1
Lymphovascular Invasion
• Lymphovascular invasion is found in 12–32
percent of T1 rectal cancers and is a strong
predictor of lymph node metastasis with an
odds ratio between 3.0 and 11.5 reported on
multivariate analysis.
• The predicted incidence of local recurrence at
36months following TEM, based on depth of
invasion, lymphatic invasion, and tumor diameter, is shown in Table29.1.
Poor Dierentiation
• Poorly differentiated histology also predicts
for lymph node metastases in rectal cancer;
however this trait is seen infrequently, present
in only 2–4% of early rectal cancers. Odds
ratio for probably poorly differentiated tumors
having lymph node metastasis is 4.8–6.1.
Tumor Budding
• Tumor budding, dened as small nests of ve
or more, usually poorly differentiated, cancer
cells along the invasive front, is a histologic
trait not routinely mentioned on biopsy reports
in North America but has been extensively
reported in the Asian gastroenterology literature as a strong predictor of lymph node
metastasis in colon and rectal cancer. Tumor
budding is present in 16–25% of T1 cancers,
and multivariate analysis has demonstrated an
odds ratio of 5.1–5.8in predicting lymph node
metastasis.
Location andMucinous Histology
• Location of the cancer within the rectum may
also be a risk factor for lymph node metastasis. Distal rectal cancers may have up to a
threefold increased risk of mesorectal lymph
node metastasis as compared to mid and proximal rectal cancers. Mucinous histology and
gender have not consistently been associated
with increased risk of lymph node metastasis.
Molecular markers are not yet able to reliably
predict nodal status. (Fig.29.5)
Imaging forEarly Rectal
Cancer Staging
• Imaging is a standard recommendation for
the staging of rectal cancer. At present, rectal
endoscopic ultrasound (EUS) is the imaging
modality of choice to distinguish between T1
and T2 rectal cancers. CT scan and MRI do
not have adequate resolution to differentiate
between layers of the bowel wall in T1 and
T2 rectal cancers, but they are better than
EUS at determining deeper T3 and T4
tumors.
404
Lymphatic invasion
Submucosal In
0246 810121416
M. H. Whiteford
vasion ≥ 1mm
Tumor budding
Poorly differentiated
Lymphovascular invasion
SM1 vs SM2/3
Vascular invasion
Fig. 29.5 Relative risk (95% condence intervals) of
lymph node metastases in pT1 rectal cancers. SM1,invasion into supercial third of submucosa. SM2/3,invasion
into middle and deep third of submucosa. (With permission from Bosch SL, Teerenstra S, de Wilt JH, Cunningham
• Despite innumerable technological advances
in medicine, however, imaging remains an
unreliable and inadequate measure of lymph
node metastasis for rectal cancer. Imaging features that are suspicious for malignant lymph
nodes include the presence of a round shape,
internal heterogeneity, and irregular border
and, to a lesser extent, size.
• Lymph node size alone is not a reliable indicator of node positivity, but nodes greater than
8 mm are considered highly suspicious on
EUS, CT, and MRI.
• MRI and EUS are the more reliable modalities
for assessing lymph node metastasis in early
rectal cancer. CT and MRI are more accurate
than EUS in the setting of locally advanced
and metastatic disease.
Oncologic Results Following Local
Excision ofRectal Cancer
• As noted above, the methodology of many
reported series of local excision for rectal neoplasia is suspect. In addition to the problems
noted above, trials of local excision for rectal
cancer suffer from additional issues.
– One problem is inclusion of patients who
have cancer in a polyp that is completely or
C, Nagtegaal ID.Predicting lymph node metastasis in pT1
colorectal cancer: a systematic review of risk factors providing rationale for therapy decisions. Endoscopy. 2013
Oct;45(10):827–34)
mostly removed by endoscopic polypectomy, and local excision is performed for
unclear margins. Many of these patients will
have no residual tumor in the local excision
specimen and have an extremely low risk of
local pelvic failure, biasing the results of the
series in favor of local excision.
– Another problem is retrospective subgroup
analysis, in which patients are only
included in the analysis after review of the
histology. This allows for exclusion of
patients who have positive margins of
resection, greater than T1 stage, or other
unfavorable histologic features. This obviously biases the analysis in favor of local
excision but fails to replicate the true
clinical situation in which margins and T
stage cannot be known with certainty
preoperatively.
– Nonrandomized comparative trials of local
excision versus proctectomy suffer from
lack of information regarding mesorectal
nodal status in the local excision group,
which would most likely favor proctectomy. Although this bias can be mitigated
by inclusion of patients in each group
based on T stage alone, it cannot be completely eliminated as there may be hidden
selection bias.
29 Local Excision ofRectal Neoplasia
405
• It is thus difcult to make rm conclusions
regarding the optimal place for local excision
in our armamentarium of therapies for patients
suffering from rectal cancer.
Local Excision forT1 Cancer
• Local excision of T1 rectal cancer is a widely
available and technically feasible procedure
with low risk of short-term morbidity and
mortality. Approximately 15% of all rectal
cancers present at stage 1 with no metastatic
lymph nodes and tumor conned to the bowel
wall. In theory, these patients will gain no
clinical benet from the lymphadenectomy
associated with a low anterior or abdominoperineal resection.
• The reported rate of local recurrence following transanal excision varies considerably in
the literature but is universally higher than for
proctectomy. For these reasons, proctectomy
remains the oncologic gold standard for rectal
cancer surgery.
• However, despite the oncologic advantages
of proctectomy as compared to local excision, it remains unclear as to whether the
oncologic benet translates into a survival
benet for select patients with small, apparently low-risk tumors. Data regarding this
topic have been of moderate to low quality
and conicting.
Local Excision forT2NX Cancer
• The deeper T2 rectal cancers invade into the
muscularis propria permitting them greater
access to the lymphatics. As a consequence,
the incidence of lymph node metastasis and
local recurrence is double that of T1 cancers.
Proctectomy is the oncologic procedure of
choice.
• However, as with T1 cancers, organ-sparing
options have been explored in conjunction
with the use of neoadjuvant or adjuvant
chemoradiotherapy.
– Preoperative chemoradiotherapy
• Advantage: better prediction of nodal
metastasis rate based on response to
neoadjuvant therapy (i.e., ypT0–1
tumors have very low rates of ypN+
status)
• Disadvantage: problems with healing of
TAE site
– Postoperative chemoradiotherapy
• Advantage: better assessment of presenting T stage and histologic features
and better wound healing
• Disadvantage: unknown response to
chemoradiotherapy and less accurate
prediction of nodal status
• At present, transanal excision and chemoradiotherapy for cT2 or pT2 tumors should be
reserved for patients unt or unwilling to
undergo proctectomy.
Surveillance andSalvage Following
Local Excision ofRectal Cancer
• Surveillance following local excision is recommended to assess for early identication of
local recurrence. It should be understood that
if the margins of resection were negative, then
the recurrence will begin in the mesorectum
and only be apparent luminally at a late stage.
• No formal guidelines are in place, but a summary of several retrospective series suggests a
follow-up strategy of proctoscopy or exible
sigmoidoscopy with high-resolution rectal
MRI or endorectal ultrasound every
3–6months for 3years; then q 6–12months
through year 5; colonoscopy at years 1, 4, and
9; and CT of the abdomen and chest annually.
• Median time to recurrence diagnosis ranges
from 13 to 47 months with most discovered
between 12 and 24 months. The addition of
radiation therapy often delays identication of
local recurrence an additional 1–2years.
• Despite close follow-up, recurrences have a
relatively poor prognosis. Patients with local
only recurrences who were candidates for
resection had an R0 resection in 79–96% of
406
M. H. Whiteford
cases resulting in a 53–58% disease-free
survival.
• These poor results of salvage therapy should
provide a sobering reminder that the best
chance of curing a patient suffering from rectal cancer is with initial treatment. Trying to
“mop up” after local pelvic or distant failure
has occurred is often futile. In addition, it
should be remembered that patients undergoing local excision are typically those with the
smallest, early-stage lesions and those most
easily cured by proctectomy.
Complications ofTAE
• Complications following local excision of rectal polyps and cancers occur in 5–25% with
mortality rates in the 0.3–0.6% range.
– Bleeding
– Peritoneal entry
– Urinary retention
– Transient fecal incontinence
Rectal Cancer: Watch andWait
GeorgeJ.Chang
30
Key Concepts
• Pathologic complete treatment response following neoadjuvant chemoradiation therapy
and surgery for rectal cancer is associated
with favorable prognosis.
• Pathologic complete treatment response is
observed in approximately 10–20% of rectal
cancer patients following chemoradiation
therapy.
• Clinical and radiographic assessment of neoadjuvant therapy treatment response is suboptimal and remains a primary challenge for safe
implementation of watch and wait strategies.
• Approximately one in three patients exhibiting clinical complete response will develop
tumor regrowth.
• At present, watch and wait should be offered
to patients only in the context of a clinical
trial.
• Local excision following neoadjuvant chemoradiation therapy may help predict mesorectal
nodal status but is associated with signicant
risk for pain and poor wound healing.
Introduction
• Despite advances in rectal cancer treatment,
multimodal therapy for rectal cancer is associated with a signicant impact on long-term
functional and quality-of-life outcomes
including risks for bowel, bladder, and sexual
dysfunction, pain, and potential need for permanent colostomy. Therefore there is great
interest in strategies to decrease the toxicity of
treatment, including strategies that employ the
selective use of radiation, chemotherapy, or
even surgery.
• The modern concept of selective use of surgery
following chemoradiation therapy for patients
with rectal cancer is based on the fact that
pathologic complete response (pCR) is
observed in approximately 10–20% of patients
following long-course chemoradiation therapy.
• While denitive surgical resection remains the
standard of care for all patients with nonmetastatic rectal cancer, a growing number of studies are providing supportive evidence for a
watch and wait, organ-preserving approach in
highly selected patients with rectal cancer
who have a complete clinical response to
chemoradiotherapy.
G. J. Chang (*)
Department of Surgical Oncology, The University
of MD Anderson Cancer Center, Houston, TX, USA
e-mail: gchang@mdanderson.org
© 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_30
407