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410 J.E. Efron and J.J. Nogueras
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30
Surgical Treatment of Rectal Cancer
Ronald Bleday and Julio Garcia-Aguilar
Approximately 42,000 patients each year are diagnosed with
rectal cancer in the United States. Approximately 8500 die of
this disease. Despite remarkable recent advances in new
oncologic agents for the treatment of colon and rectal cancer,
cure is almost never achieved without surgical resection.
However, the current management of rectal cancer is now
more varied and complex because of the new approaches with
multimodality therapy and the refinements in surgical techniques. For example, small distal rectal cancers with minimal
invasion can be treated with a local excision with or without
adjuvant therapy. More proximal or more invasive tumors
require a “radical” resection. The two most common procedures are the low anterior resection (LAR) and the
abdominoperineal resection (APR). Extended resections are
occasionally required for patients with cancers that invade or
adhere to adjoining structures such as the sacrum, pelvic
sidewalls, prostate, or bladder.
This Chapter discusses the surgical management of rectal
cancer including a basic review of the preoperative evaluation
and how it pertains to surgical planning, the preoperative
preparation, the surgical procedures, the biology of rectal
cancer as it relates to surgery, the issue of margins,
and the technical nuances that need to be appreciated for a
successful resection.
Evaluation of the Patient with Rectal
Cancer
History
The patient with rectal cancer usually presents to the surgeon after a definitive endoscopic diagnosis. The patient’s
initial complaint may have been rectal bleeding, a change in
bowel habits, or a sense of rectal pressure. However, with
the increase in surveillance colonoscopy, many patients are
completely asymptomatic on presentation. During the initial
history, the surgeon should ask about certain symptoms
because it will aid in selecting the best therapy for the
patient. For example, tenesmus (the constant sensation of
needing to move the bowels) is often indicative of a large
cancer. Constant anal pain or pain with defecation suggests
invasion of the anal sphincters or pelvic floor. Preemptive
procedures such as a diverting colostomy may be required in
patients with these distal painful cancers. Also, cancers
growing into the anal sphincter are not candidates for a
sphincter-sparing procedure. Questions concerning a
patient’s fecal continence should also be discussed before
any therapy. Sphincter-sparing procedures can put a tremendous stress on even the most normal of pelvic floors and
anal sphincters. A history of significant continence problems should prompt a discussion with the patient concerning
quality of life issues. Sphincter-sparing surgery in these
patients, even if technically possible, often leads to significant fecal soiling and the patient may be better served with
a resection and permanent colostomy.
Physical Examination and Rigid
Sigmoidoscopic Examination
A digital rectal examination (DRE) and a rigid sigmoidoscopy are essential to the surgical decision-making process.
Both a proper examination and rigid sigmoidoscopy should
be performed on the initial patient visit unless the patient has
a painful invasive lesion. On DRE, fixation of the lesion to the
anal sphincter, its relationship to the anorectal ring (the collection of muscles that make up the sphincters), and possible
fixation to both the rectal wall and the pelvic wall can be
evaluated. For mid rectal or upper rectal lesions, the DRE and
rigid sigmoidoscopy can help determine how much normal
rectum lies distal to the lower border of the tumor. With the
combination of DRE and sigmoidoscopy at the initial visit,
the surgeon can often determine whether a patient is a candidate for sphincter-sparing surgery, whether a temporary
diverting ostomy is likely, and what anorectal function will be
like post-treatment.
413
414 R. Bleday and J. Garcia-Aguilar
Colonoscopy
A colonoscopy should be performed before surgical resection
of a rectal cancer. Colonoscopy allows for confirmation of a
malignancy through biopsy and the diagnosis and possible
removal of synchronous colonic lesions. Synchronous benign
polyps have been reported in 13%–62% of cases and synchronous cancers have been reported in 2%–8% of cases.
1–6
Even if a colonoscopy has been recently performed on a
patient, the surgeon should still perform a rigid sigmoidoscopy because estimates of the location of the lesion are
often misleading. For example, because of the flexibility of
the colonoscope, a lesion that is described as 15 cm from the
anal verge can sometimes be a close as 5 cm from the anal
verge when evaluated with the rigid scope. Finally, both with
a colonoscope and rigid sigmoidoscope, one should describe
the distance from the lower border of the lesion to a standard
distal landmark. The National Cancer Institute (NCI) consensus group recommends the use of the “anal verge” as the starting point for measuring distance; however, this anatomic
landmark is variable. An alternative is to use the dentate line
as the zero point and measure the distance from the lower border of the lesion to the proximal border of the anorectal ring.
This distance is essentially a measure of the maximal amount
of rectum that one can resect before considering an APR.
Preoperative Staging
Preoperative staging of a patient with a rectal cancer is
becoming essential in the decision-making process as adjuvant modalities become increasingly used preoperatively.
Also, the range of surgical procedures that can be offered to a
patient is in part dependent on the preoperative imaging. For
a basic evaluation, all patients should receive a chest X-ray or
chest computed tomography (CT) scan to exclude pulmonary
metastases. One can obtain a carcinoembryonic antigen
(CEA) level. If increased preoperatively, the CEA level
should decrease to the normal range after treatment. CEA can
then be followed postoperatively to detect a recurrence. Most
other laboratory evaluations obtained preoperatively are useful for determining pertinent medical problems but are not
very helpful in staging. By far, the most useful staging for
rectal cancer is abdominal/pelvic imaging with CT, magnetic
resonance imaging (MRI), or ultrasound (US)
Imaging for Rectal Cancer
Pretreatment abdominal and pelvic imaging of the patient
with rectal cancer is necessary in this era because of the
increasing value of preoperative adjuvant therapies. Therapy
differs depending on stage, depth of invasion into the rectal
wall within a stage, size of lesion, and location of the tumor.
In particular, distal and mid rectal cancer treatment management will differ depending on the preoperative staging and
imaging. For upper rectal cancers, imaging to determine stage
will often not influence the treatment plan. Many of these
patients with upper rectal tumors will benefit from an LAR
regardless of the stage and may not require neoadjuvant
therapy as often as low and mid rectal cancers.
CT Scans
Differing opinions exist as to whether a CT scan is a useful
routine assessment modality in a patient diagnosed with a rectal cancer. Some would argue that for routine, uncomplicated
malignancies, a CT scan is generally not necessary, because
the information obtained will not usually affect the treatment
plan. This concept is probably more applicable to patients
with colon cancers versus patients with rectal cancers. For
rectal cancer, there may be some merit to a baseline preoperative CT scan for advanced lesions. CT scanning is quite
accurate in assessing rectal tumors that have invaded adjacent
organs. However, for assessment of small primary lesions, CT
scanning has many limitations. CT scans do not effectively
visualize the layers of the rectal wall and so do not help in
evaluating the extent of rectal wall invasion of an early cancer. The overall accuracy of CT scanning in determining
depth of invasion is approximately 70%. Additionally,
CT scanning is limited in its ability to determine the presence
or absence of lymph node metastases. Overall accuracy with
CT scanning for assessing lymph nodes in rectal cancer is
only 45%.
7–11
The most current CT scanning, especially with dynamic
contrast infusion, has a high accuracy rate in detecting liver
metastases. However, abdominal US, similar to CT scan,
can also detect occult liver metastases and should be used
when the information obtained would alter therapeutic deci-
12
sions.
MRI is also very useful in evaluating the liver before
resection.
Endoluminal Imaging
Endoluminal imaging in the form of endoluminal US and
endoluminal MRI has become extremely useful in the accurate preoperative staging of a rectal cancer. These modalities
allow for more precise determination of the depth of invasion
and the presence or absence of mesorectal lymph node metastasis. The knowledge of these factors is critical in determining
the sequence and type of therapy for any given rectal cancer.
Endoscopic US is performed with a probe that is inserted
into the rectum via the anus. The patient usually has taken a
small preparation to clear the rectum of stool. A water-filled
balloon is inflated and pressed against the rectal lesion. A 7.0to 10.0-MHz transducer is then used to delineate the layers of
the bowel wall into five distinct lines. Localized cancers
involving only the mucosa and submucosa can therefore be
distinguished from those tumors that penetrate the muscularis
propria or extend through the rectal wall into the perirectal
13
fat.
A modified TNM classification has been proposed,
14,15
30. Surgical Treatment of Rectal Cancer 415
in which a US stage T1 lesion (uT1) denotes a malignancy
confined to the mucosa and submucosa, a uT2 lesion implies
penetration of the muscularis propria, but confinement to the
rectal wall, a uT3 lesion indicates invasion into the perirectal
fat, and a uT4 lesion denotes a primary rectal malignancy that
invades an adjacent organ. Studies have compared endorectal
US (ERUS)
16,17
to DRE17and have found the US much more
accurate. In a recent metaanalysis review, endoluminal US
was found to be 95% accurate in distinguishing whether a
tumor was confined to the rectal wall (T1, T2) versus invasion
into the perirectal fat (T3 or greater).
18
ERUS is less useful in predicting lymph node metastases
19
with 80%–85% accuracy.
Endosonographically identified
malignant lymph nodes are generally more hypoechoic in
perirectal tissues.
20
However, these results are only seen with
experienced operators.
Two methods of MRI can be used for the evaluation of rectal cancer. One can use the endorectal coil (ecMRI) or the surface coil MRI. The use of the MRI, either the endorectal or
the surface coil, may offer some advantages compared with
ERUS. First, it permits a larger field of view. Second, it may
be less operator and technique dependent. And third, using
the MRI may allow for the study of stenotic tumors.
21–24
Similar to ERUS, endorectal MRI (eMRI) can stage smallvolume nodal disease and subtle transmural invasion. In general, eMRI has been more helpful in the assessment of
perirectal nodal involvement than T stage. One reason is that
MRI can identify involved nodes on the basis of characteristics other than size.
nodal staging range from 50% to 95%.
25
Reported accuracy rates of MRI for
24-27
Several series have compared the preoperative staging
accuracy of ecMRI to ERUS in patients with rectal can-
24,26–28
cer.
In a report of 89 patients, the overall accuracy for
T staging was similar (81%) for ecMRI and ERUS compared
with only 65% for CT.
29
The accuracy for N staging was
equally poor among the three modalities (63%, 64%, and 57%
for ecMRI, ERUS, and CT, respectively). Somewhat similar
results were noted in a series of 49 patients.
28
Transmural penetration was predicted by ecMRI with equal sensitivity (89%),
but higher specificity (65% versus 33%) than ERUS. With
both techniques, the predicted N stage had a relatively low
correlation with pathologic N stage (45% versus 53%). In one
report of 21 patients, ERUS seemed to be superior to ecMRI
for determination of pathologic T stage (accuracy 83% versus
40%) because of better differentiation between T1 and T2
tumors. The accuracy for detecting perirectal tumor infiltration was 80% for ecMRI versus 100% for ERUS.
27
The ecMRI is less operator dependent and in answering the
critical question of whether a patient has Stage I versus Stage
II or Stage III disease, ecMRI was 88% accurate. Those
patients who were not staged correctly were usually overstaged and not understaged.
Double contrast MRI may permit more accurate T staging
of rectal cancer by allowing better distinction among mucosa,
muscularis, and perirectal tissues.
30,31
The specificity and
sensitivity of ecMRI to predict infiltration of the anal sphincter was 100% and 90%, respectively. However, N staging was
not improved with this approach; the sensitivity and specificity for nodal disease being 68% and 24%, respectively.
Phased-array surface coil MRI may prove to be the option
of choice for staging of more advanced rectal cancers. The
technique has been useful in predicting the likelihood of a
tumor-free resection margin by visualizing tumor involvement
of the mesorectal fascia.
32
Preparation of the Rectal Cancer Patient
for Surgery
After the diagnosis and staging of a rectal cancer, a decision
needs to be made regarding optimal method of treatment. The
surgical approach is dependent on the location of the tumor,
its depth of invasion, and whether, in the preoperative evaluation, metastases have been discovered. Whether the patient is
a candidate for a local excision or for a radical resection, the
patient needs to be prepared for the procedure and the anesthetic so as to minimize perioperative and postoperative complications. Particular attention needs to be given to the
patient’s medical comorbidities. Unique to colon and rectal
surgery is the need for a bowel preparation.
Bowel Preparation
Before the use of mechanical preparations and perioperative
antibiotics, infection rates after colorectal surgery ranged as
high as 60%.
mechanically cleanse the large intestine. These include a diet
of clear liquids 1–3 days before surgery combined with one of
the following: laxatives, enemas, wholegut irrigation with
saline via a nasogastric tube, mannitol solutions, polyethylene
glycol (PEG) electrolyte lavage solutions, or PEG-based
tablets. In a survey of colon and rectal surgeons in 1990,
almost two-thirds preferred the PEG solutions for their
patients because of the reliability of the cleansing results.
Many surgeons today continue to use these PEG solutions as
a bowel preparation. There have been two recent metaanalyses that have concluded that mechanical bowel cleansing
before colorectal surgery has no significant impact on perioperative infection rates.
would still recommend that some type of colonic cleansing
occur before surgery because it is easier to manipulate the
bowel if it is not filled with stool. It should be emphasized that
one should not force a preparation on a patient because the
benefits may be minimal. Furthermore, the choice of preparation should be selected depending on the individual. For
instance, large-volume lavage solutions should not be used in
patients with gastric emptying problems such as gastroparesis
caused by diabetes. Saline laxatives are often phosphate- or
magnesium-based and should not be used in patients with
renal failure.
33,34
Currently, there are several methods used to
36,37
Despite these recent studies, we
35
416 R. Bleday and J. Garcia-Aguilar
Antibiotic Prophylaxis
After mechanical cleansing of the large intestine, antibiotic
prophylaxis is used to decrease the incidence of postoperative
septic complications, because mechanical cleansing decreases
the total volume of stool in the colon but does not affect the
concentration of bacteria per milliliter of effluent.
38
Traditional
prophylaxis uses an oral regimen known as the Nichols/Condon
preparation. This regimen consists of neomycin 1 g and erythromycin base 1 g by mouth at 1:00
PM, 2:00 PM, and 11:00 PM
on the day before surgery.39Many surgeons have substituted
metronidazole 500 mg for the erythromycin base because it is
bacteriocidal against a greater percentage of gut anaerobes.
Most surgeons use perioperative systemic antibiotics
instead of oral antibiotics for antibiotic prophylaxis. Regimens
need to include coverage for both aerobic and anaerobic gut
bacteria. For long procedures, redosing should be considered
depending on the serum half-life of the antibiotics used. Some
have argued that double prophylaxis with both oral and intravenous antibiotics is of benefit in immunocompromised
patients or in patients in whom the dissection is below the
peritoneal reflection.
Other Perioperative Issues
Besides the mechanical and antibiotic preparation of the
bowel, all patients are prepared in the usual manner for major
surgery. Blood loss is usually quite minimal for most elective
colorectal surgery and typically patients are not asked to
donate autologous blood. Cardiac, pulmonary, and nutritional
evaluations are performed when necessary. Perioperative systemic antibiotic coverage is expanded in patients with highrisk cardiac lesions such as prosthetic heart valves, a history of
endocarditis, or a surgically constructed systemic-pulmonary
shunt, and with intermediate-risk cardiac lesions such as mitral
valve prolapse, valvular heart disease, or idiopathic hypertrophic subaortic stenosis.
38
Intravenous ampicillin 2 g and
gentamicin 1.5 mg/kg are given 1/2–1 hour before the procedure and for at least one postoperative dose. Oral anticoagulation is stopped, and patients are placed on intravenous
anticoagulation or on Lovenox approximately 5 days before
surgery. The heparin or Lovenox is then stopped at the appropriate time before surgery (8 or 12 hours, respectively).
Depending on the individual risk of the patient and the extent
of the operative dissection, anticoagulation is restarted as early
as 8 hours postoperatively, but without a bolus. Careful monitoring of the patient’s hematocrit and partial thromboplastin
time are necessary if early reheparinization is instituted.
Anatomic and Biologic Issues
Surgical Anatomy
The type of operation that can be offered to a patient with rectal cancer depends not only on tumor stage, but also on the
location of the tumor in relation to the surgical anatomy.
Surgical anatomy refers to the anatomic landmarks that determine resectability and sphincter preservation. The NCI consensus on rectal cancer recommended localizing the tumor
relative to the anal verge which is defined as starting at the
intersphincteric groove. Another important landmark defining
the upper limit of the anal canal is the anorectal ring. From the
surgeon’s perspective, the top of the anorectal ring is the
lower limit of a distal resection margin. A large, full-thickness
cancer needs to be located high enough above the top of the
anorectal ring to allow for an adequate distal margin if sphincter preservation is contemplated. If the dissection is to be carried lower toward the dentate line, then the tumor must be
confined to the mucosa, submucosa, and superficial layer of
the internal sphincter.
Biologic Issues
It is important to understand the clinical biology of rectal cancer. “Clinical” biology, means the typical pattern of growth
and natural history of the spread of the disease. Studies have
shown that colon cancer frequently arises in adenomatous
polyps of the colon or rectum. Also, there is a 13%–62% incidence of polyps in patients with carcinoma of the colon or
rectum.
isting adenomas with carcinoma of the colon or rectum
depends in part on the method of study.
used to study the issue, one can clearly say that the vast
majority of carcinomas arise in preexisting adenomas.
preparing a patient for surgery, the surgeon should have the
colon completely evaluated preoperatively so as to be able to
operatively treat any synchronous disease that cannot be
removed endoscopically.
cancer is important to note and is somewhat different from
that of other solid tumors such as breast cancer. Gabriel
et al.
have “skip” metastases. Rectal cancers usually proceeded in
an orderly march from the adjacent mesorectal nodes up the
lymphatic chain to the upper extent of the mesentery along
the inferior mesenteric artery (IMA) and vein systems. From
the surgeon’s perspective, this means that early intervention
along with proper locoregional resection will cure most cancers. As part of a multimodality team that now treats most
solid tumors, it must be emphasized to our medical colleagues that a rectal cancer is not a systemic disease from the
first abnormal cell division. Aggressive local therapy in the
form of an adequate resection is still the “anchor” to any
therapy.
with certain polyposis syndromes or in cancers associated
with inflammatory bowel disease. With both of these conditions, a total proctocolectomy needs to be performed.
Sphincter preservation can be considered in certain patients
but one needs to recognize that any mucosa left intact is at an
increased risk of developing cancer. The anal transitional
zone needs to be biopsied to identify dysplasia. If dysplasia is
40–43
The variation observed in the incidence of coex-
1,2
Whatever method
44–46
In
The biology of lymph node metastases with invasive rectal
47
reported in 1935 that colorectal cancers tend not to
Surgical therapy may need to be customized in patients
30. Surgical Treatment of Rectal Cancer 417
present, then a proctocolectomy with end ileostomy needs to
be performed.
Surgical Procedures: Principles
Resection of the bowel with primary anastomosis was not a
common phenomenon until the late 1940s. Before that time,
surgery of the colon and rectum usually meant a permanent
48
stoma.
techniques for rectal cancer. The result is that primary resection and anastomosis without a colostomy or ileostomy is
now the rule rather than the exception.
tive resection is not possible. If the patient is a reasonable
operative risk and the extent of metastatic disease is minimal,
then complete but palliative resection of the primary tumor
leads to a better quality of life and prevents many of the distressing symptoms of an advanced primary lesion such as
obstruction, bleeding, and pain. If the primary lesion is not
resectable, then diversion of the fecal stream can significantly improve the patient’s immediate status. Nonoperative
therapy should be considered when there is significant
metastatic disease and the primary tumor is relatively small
and uncomplicated. In this situation, it is likely that the
patient will die of metastatic disease before a complication
from the primary tumor.
Variability in Outcome Based on Surgeon
and Hospital Volume
The cancer resection margin in the extraperitoneal rectum is
limited by the bony confines of the pelvis as well as by
the proximity of adjacent anterior organs. In some cases,
locoregional recurrence may be inevitable. However,
locoregional failure may also result from incomplete surgery. There is accumulating evidence of variability among
surgeons in local recurrence rates for stage-matched rectal
cancers. McArdle and Hole
patients undergoing colorectal cancer resection at the Royal
Infirmary in Glasgow. They observed significant variability
in patients’ postoperative morbidity, mortality, and ultimate
survival, depending on the surgeon. The proportion of
patients undergoing a curative resection varied from 40% to
76%, operative mortality from 8% to 30%, local recurrence
from 0% to 21%, and anastomotic leak rates from 0%
to 25%.
rates, postoperative mortality, and overall survival as shown
in a series of 7257 patients diagnosed with Stage I–III rectal
cancer between 1994 and 1997.
highest quartile of volume (more than 20 procedures annually) were compared with those with volumes in the lowest
quartile (fewer than seven procedures annually), there were
Recent advances have been made in the surgical
Palliation should be the goal in a patient for whom cura-
49
presented a review of 645
Hospital volume can also have an impact on colostomy
50
When hospitals with the
statistically significant differences in colostomy rates
(29.5% versus 36.6%), 30-day postoperative mortality
(1.6% versus 4.8%), and in overall 2-year survival (83.7%
versus 76.6%).
The ability to perform sphincter-sparing surgery is also
affected by hospital volume. In the United States Intergroup
0114 trial of 1330 patients with Stage II or III rectal cancer
participating in an adjuvant treatment trial, APR rates
were significantly higher in low-volume hospitals (46%
versus 32% at lowest and highest volume hospitals, respec-
51
tively).
Low hospital surgical volume was only an important predictor of inferior overall or recurrence-free survival in
patients who did not complete their planned adjuvant
chemoradiotherapy.
Total Mesorectal Excision
Total mesorectal excision in conjunction with an LAR or an
abdominal perineal resection involves precise sharp dissection and removal of the entire rectal mesentery, including
that distal to the tumor, as an intact unit.
tional blunt dissection, the rectal mesentery is removed
sharply under direct visualization emphasizing autonomic
nerve preservation, complete hemostasis, and avoidance of
violation of the mesorectal envelope. Its rationale is underscored by the hypothesis that the field of rectal cancer
spread is limited to this envelope and its total removal
encompasses virtually every tumor satellite. The reduction
of positive radial margins can be reduced from 25% in
conventional surgery to 7% in cases resected by TME.
Furthermore, Adam et al.
53
showed that patients with positive radial margins were 3 times more likely to die and 12
times more likely to have local recurrence than patients
without radial margin involvement.
Conventional surgery violates the circumference of the
mesorectum during the blunt dissection along undefined
planes. This leaves residual mesorectum in the pelvis. The
higher rate of pelvic recurrence in conventional surgery is a
reflection of inadequate resection and residual viable tumor
burden within the pelvis. Several surgical teams using the
TME technique have reported local failure rates ranging from
5% to 7% for Stage II and Stage III cancers.
the North Central Cancer Treatment Group, NCCTG, control
arm consisting of surgery plus radiotherapy had a local failure
rate of 25% and the addition of chemotherapy only decreased
the local failure rate to half that value.
Of greater importance is the fact that improved local control seems to be translatable into improved overall survival.
Survival ranges from 68% to 78% are observed among large
published series when this technique is applied.
The meticulous dissection, however, is not without consequence. Prolonged operative time and increased anastomotic
leak rates are noted. Anastomoses 3–6 cm from the anal verge
have led up to 17% leak rates. Some centers are now routinely
fashioning a protective diverting ostomy.
52
52–56
57
Unlike conven-
By contrast,
418 R. Bleday and J. Garcia-Aguilar
Conventional rectal surgery is associated with a significant
incidence of sexual and urinary dysfunction. Presumably, this
is related to damage to the pelvic autonomic parasympathetic
and sympathetic nerves by blunt dissective forces.
Postoperative impotence and retrograde ejaculation or both
have been observed in 25%–75% of cases particularly if lateral wall lymphadenectomy and splanchnic nerve resection
are performed. By contrast, after TME with its careful nervesparing dissection, impotence has been reported in only
10%–29% of cases. A recent prospective study confirms that
autonomic nerve preservation yields good results in terms of
morbidity and functional outcome.
59
There are well-recognized points during the rectal dissection where nerve injury can occur. The most proximal is the
sympathetic nerve plexus surrounding the aorta. These sympathetic nerve trunks are also prone to injury near the pelvic
brim as the bifurcate to each side of the pelvis. Intact nerves
should look like a “wishbone” near the sacral promontory
after a proper dissection. The clinical consequence of an isolated sympathetic nerve injury is retrograde ejaculation. If
one proceeds with a dissection beneath the presacral or
pelvic fascia from the sacral promontory around to the lateral pelvic sidewall, then one can injure both parasympathetic and sympathetic nerves which can result in impotence
and bladder dysfunction. In the lower part of the mid
rectum, the hypogastric plexus and nervi erigentes can be
injured in the anterolateral pelvis. A radial dissection well
outside the lymphovascular bundle which lies adjacent to
the nerve and nerve plexus can also lead to a mixed
parasympathetic and sympathetic injury. This bundle and
the nerve structure are typically located just lateral to the
seminal vesicles in a man or the cardinal ligaments in a
woman. Finally, a dissection anterior to both layers of
58
Denonvillier’s fascia in a man can also put at risk the nerve
and nerve plexus.
To date, all data are from prospectively gathered series and
comparisons with historical controls. There are no randomized control data clearly showing benefits in terms of diseasespecific and overall survival in patients undergoing TME as
opposed to more conventional resection.
Adjuvant therapy has recently been shown to improve the
results of TME surgery. In a two-arm, randomized study comparing TME with or without preoperative radiotherapy for
resectable rectal cancer, patients receiving the combined therapy had a lower rate of local recurrence at 2 years. Subset
analysis showed the most significant benefit in node-positive
cancers.
with prognosis.
60
The “completeness” of the TME also correlated
61
Adjuvant therapy should therefore be considered in patients undergoing TME surgery with Stage II and
Stage III disease.
Figure 30-1 demonstrates schematically how the dissection
should proceed. Figure 30-2 shows a cross-section of the rectum, the mesorectal fat, and the associated fascia.
Distal Margins and Radial Margins
The extent of resection margins in rectal cancer remains controversial. Although the first line of rectal cancer spread is
upward along the lymphatic course, tumors below the
peritoneal reflection also spread distally by intramural or
FIGURE 30-1. Schematic representation of the correct TME dissection versus an incorrect dissection. The dissection should proceed between
the mesorectal fascia and the pelvic wall fascia to ensure a “complete” TME.
30. Surgical Treatment of Rectal Cancer 419
ence in local recurrence rates whether distal margins of <2 cm,
2–5 cm, or >5 cm were achieved. Finally, in two early studies
from the British literature, surgical pathology of rectal and rectosigmoid cancer demonstrated the clinical biology of extra-
67
mural lymphatic spread. In the series by Goligher et al.
from
1951, only 6.5% of patients had metastatic glands below the
primary tumor, whereas 93.5% had no retrograde spread.
Approximately two-thirds of patients with retrograde spread
had metastasis limited to within 6 mm of the distal tumor edge,
and only 2% had metastasis beyond 2 cm. Dukes
68
published
similar results in a study of more than 1500 patients with
abdominoperineal cancer.
Further data from a randomized, prospective trial conducted by the National Surgical Adjuvant Breast and Bowel
Project demonstrated no significant differences in survival or
local recurrence when comparing distal rectal margins of <2
cm, 2–2.9 cm, and >3 cm.
69
As a result, a 2-cm distal margin
has become acceptable for resection of rectal carcinoma,
70
although a 5-cm proximal margin is still recommended.
The
radial margin is more critical for local control.
It seems reasonable to conclude that a 2-cm distal margin
is justified over a 5-cm distal margin. Even smaller distal
margins may be acceptable in certain patients for whom there
is no other option for sphincter preservation. In these cases, a
frozen section analysis of the distal margin must be
performed to confirm a cancer-free margin.
The discussion concerning the distal margin should not be
FIGURE 30-2. Transverse diagram of the structures of the mid rectum.
The proper dissection proceeds just outside the mesorectal fat and fascia but with sparing of the neurovascular bundle and hypogastric plexus
that is located anterolaterally along the pelvic sidewall. One or both
layers of Denonvillier’s fascia should be included in males and the
equivalent fascial dissection along the back of the vagina in females.
confused with the issues regarding a TME and the radial margin. It is now clear that the status of the radial margin is perhaps the most critical in determining prognosis. Quirke et al.
in 1986 demonstrated tumor spread to the radial margins of 14
of 52 rectal cancers on whole mount specimens (27%). Twelve
of these 14 patients subsequently developed local recurrence
suggesting that local recurrence is largely a result of radial
55
also documented that tumor involveextramural lymphatic and vascular routes. When distal intramural spread occurs, it is usually within 2.0 cm of the tumor,
unless the lesion is poorly differentiated or widely metasta-
62–64
tic.
Williams et al,65in 1983 reported distal intramural
spread in 12 of 50 resected rectal cancer surgical patients. It
was observed that 10 of the 12 had Stage III lesions. Only 6%
had distal intramural spread greater than 2 cm. They concluded a “wet” margin of 2.5 cm was adequate in 94% of the
patients. They noted that only five patients (10%) had tumor
beyond a 1.5-cm margin, and all five of these had poorly differentiated, node-positive cancers. Also, the mortality in this
group of patients was attributable to distant metastases, not
local recurrence. All these patients had undergone an APR and
had distal margins of greater than 5 cm. Grinnell
62
reported
five cases of extramural retrograde lymphatic spread within
1.5 cm in 93 rectal cancers. He also reviewed 28 patients with
atypical retrograde lymphatic dissemination. All these patients
died within 5 years. He concluded retrograde lymphatic spread
was a poor prognostic sign and more radical operations were
not advantageous. Pollett and Nicholls
66
observed no differ-
spread. Cawthorn et al.
ment of the lateral resection margin correlated with poor prognosis; however, it seemed to correlate more with distant spread
and it was not a useful indicator of local recurrence.
Selection of Appropriate Therapy for
Rectal Cancer
The management of rectal cancer has become increasingly
complex. Presently, a surgeon has three major curative
options: local excision, sphincter-saving abdominal surgery,
and APR. Ideal candidates for local therapy that preserves anal
sphincter anatomy and function include small T1 lesions
(invasion only into the submucosa) and T2 lesions (invasion
into the muscularis propria). As will be discussed, patients
with T2 lesions probably should not have surgery alone.
Recurrence is high. Preoperative or postoperative adjuvant
chemoradiation is of benefit. At present, patients with T3
lesions (invasion into the perirectal fat) are not suitable candidates for local therapy and should be treated with an appropriate major resection as well as adjuvant therapy in most cases.
71
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