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400 A.J. Senagore and R. Fry
general surgery program directors revealed that vascular surgeons preferred to repair the aneurysm first, whereas the non-
23
vascular surgeons preferred colectomy.
The primary risk is
that performing either operation first may cause complications that significantly delay the second procedure. The risk
of performing a colectomy synchronously with placement of
graft material is a graft infection; however, this risk does not
seem excessive based on the small data sets available.
23–27
In
all likelihood, the best guidance suggests that any aneurysm
>6 cm should be repaired first or synchronously in the face of
an associated colon cancer to avoid the risk of rupture.
Endoluminal grafting of an appropriate aneurysm may eliminate the majority of these quandaries in the future.
25
Synchronous Management of Colon Cancer
and Liver Metastases
The potential benefit of simultaneous colectomy and hepatectomy is the avoidance of two laparotomies and possible
reduction in operative risk. Conversely, delayed management
of colonic hepatic metastases offers the ability to accurately
stage patients and avoid the risk of hepatectomy in a group of
patients who will prove to have more widely metastatic disease in several months. Selection of patients who have limited
hepatic involvement and who are positron emission tomography negative for distant disease has resulted in increased
resectability and 5-year survival after hepatectomy.
28
The
risks of simultaneous colectomy and hepatectomy do not
seem to be excessive in select patients operated by expert
29–31
groups.
However, the risks may be less with smaller
nonanatomic liver resections coupled with right colectomy.
Radiofrequency ablation will be discussed in Chapter 34.
32,33
Sentinel Node Assessment
Sentinel node assessment was first described as a means of
improving staging and treatment for melanoma patients and
is currently considered standard of care for breast cancer
patients.
identification for colorectal cancer patients with proposed
benefits of a high rate of node identification and pathologic
upstaging.
of 0.5–1 cc of isosulfan blue dye subserosally at the periphery of the tumor (node visualization within 30–60 seconds),
or ex vivo injection of 1–2 cc in a similar manner after the
bowel has been resected.
nique, including some modifications, has demonstrated falsenegative rates approaching 60%, and limitations in rectal
cancers.
tation of sentinel node assessment in colorectal cancer. First,
there is no consensus of opinion regarding the prognostic significance of micrometastatic lymph nodes in colorectal
cancer, particularly those identified by immunohistochemistry
34,35
Saha described the application of sentinel node
36
The technique involves either in vivo injection
35
Subsequent evaluation of the tech-
36–38
There are several concerns that restrict routine implemen-
39–45
or polymerase chain reaction.
Second, the relatively high
false-negative rates and/or lack of node visualization mentioned previously, limit the confidence in restricting microsectioning and use of special stains to the group with stained
nodes. Finally, there is insufficient evidence that the technique is sufficiently accurate to alter the extent of surgical
resection.
46
Before sentinel node assessment can be routinely
recommended, two hurdles must be overcome: 1) provision of
incontrovertible evidence that micrometastatic disease identified by any technique correlates with survival; and 2) that the
25
survival rates can be favorably impacted by an adjuvant
chemotherapy regimen. Therefore, at the present time, routine
lymph node mapping cannot be recommended.
Outcome of Colectomy for Colon Cancer
In general, the operative outcome and long-term survival after
resection of curable colon cancer parallels the TNM and
Dukes’ stage (A1, well above 90%; B2, 65%–90%; C3,
45%–75%) which may be modulated by adjuvant chemother-
47,48
apy.
a rare occurrence and should be less than 5%.
the impact of the surgeon’s experience and the associated
expertise of the institution have recently been found to have a
profound effect on outcome. High-volume surgeons, particularly those at high-volume institutions, have demonstrated significantly lower perioperative complications and an improved
survival after colectomy for colon cancer.
for palliation should rarely be performed and only in patients
with life-threatening comorbidities or advanced incurable disease. Local extension of colon cancer may be treated with
chemoradiation initially to allow eventual resection and
primary anastomosis.
management of margins and extent of resection has a significant effect on outcome after colon cancer resection. The margins to be considered included proximal and distal bowel
margins, radial margins, and extent of mesenteric resection
which encompasses the nodal resection and proximal vascular ligation. The adequacy of proximal and distal bowel margins is primarily defined by the vascular ligation and hence
the adequacy of vascular supply to the intended anastomotic
segments. Although not clearly defined, it is generally agreed
that 5 cm proximal and distal bowel margins are sufficient to
allow resection of mural tumor spread. Grinnell originally
evaluated the patterns of mural spread of tumor in the colon
via lymphatics and found no instance of spread greater than
4 cm in the most advanced cases.
suggest that mural tumor migration is rarely greater than 2 cm
either proximal or distal to the palpable tumor edge.
Similarly, there is no need to resect any specific amount of
terminal ileum, other than defined by vascular supply because
mural spread to the ileum is a very rare event. Vascular ligation is generally performed at the origin of the primary feeder
The risk of locoregional recurrence after colectomy is
49–51
52–55
A colectomy
In addition to experience, the overall surgical approach to
56
More recent data would
However,
57
28. Surgical Management of Colon Cancer 401
vessel to a colonic segment. For resection of the right colon
and transverse colon, the debate is relatively moot because of
the constraints of the arterial origin of the right colic and middle colic arteries. Ligation for left-sided resections has been
debated, primarily in sigmoid or anterior resections because
ligation of the IMA may be performed at the aorta, or just distal to the left colic artery takeoff. A report from St. Marks
assessed this issue in 1370 patients and found that survival
was equivalent for all stages for the ligation options except for
the most advanced node positive cases who fared worse with
ligation at the aorta.
58
This counter-intuitive finding was more
likely related to the higher stage of patients identified by the
wider lymphatic resection. A comparison of left hemicolectomy and segmental colectomy (ligation of the IMA versus
more distal) by the French Association for Surgical Research
could not discern either a different survival rate or pattern
based on the ligation or resection performed.
47
demonstrated the benefits of careful surgical technique
et al.
which resulted in a complete resection of all tumor (R0).
59
Jagoditsch
49
Their data demonstrated an operative mortality of 1.3% and a
5-year survival rate of 71.8% for curative operations in Stage
I–III disease.
Summary
Surgery for colonic cancer has been increasingly better
defined and the data clearly support the benefits of wide
mesenteric resection, clear radial margins, and resection
of adherent adjacent organs. Although the precise level of
proximal vascular ligation may remain debatable, it is
equally clear that the major trunk vessel and the entire supporting mesentery should comprise the specimen. Attention
to surgical detail coupled with improved perioperative care
strategies are essential to minimizing operative morbidity
and mortality.
Appendix: Practice Parameters for
Colon Cancer
Prepared by The Standards Practice Task Force, The
American Society of Colon and Rectal Surgeons
Daniel Otchy, MD, Neil H. Hyman, MD, Clifford
Simmang, MD, Thomas Anthony, MD, W. Donald Buie, MD,
Peter Cataldo, MD, James Church, MD, Jeffrey Cohen, MD,
Frederick Dentsman, MD, C. Neal Ellis, MD, John W.
Kilkenny III, MD, Clifford Ko, MD, Richard Moore, MD,
Charles Orsay, MD, Ronald Place, MD, Janice Rafferty, MD,
Jan Rakinic, MD, Paul Savoca, MD, Joe Tjandra, MD, Mark
Whiteford, MD
I. Diagnostic evaluation
II. Preoperative assessment
Guideline—Preoperative, carcinoembryonic antigen level
should be obtained. Level of evidence (Class II, Grade A)
Guideline—Evaluation with preoperative CT scanning of
selected patients is indicated and routine preoperative CT
scanning is optional. Level of evidence (Class II, Grade B)
Guideline—Routine performance of preoperative chest
X-rays is acceptable. Level of evidence (Class III, Grade C)
III. Preparation for operation
A. Informed consent
Guideline—Informed consent should be obtained preoperatively. Level of evidence (Class III, Grade C)
B. Mechanical bowel preparation
Guideline—Mechanical bowel preparation is nearly universally used in elective surgery. Level of evidence (Class II,
Grade A)
Guideline—Outpatient bowel preparation is generally safe
and cost effective. Level of evidence (Class II, Grade A)
C. Prophylactic antibiotics
Guideline—Prophylactic antibiotics are recommended for
patients undergoing colon resection. Level of evidence (Class
I, Grade A)
D. Blood cross-match and transfusion
Guideline—Blood transfusion should be based on physiologic need. Level of evidence (Class III, Grade C)
E. Thromboembolism prophylaxis
Guideline—All patients undergoing surgery for colon cancer should receive prophylaxis against thromboembolic disease. Level of evidence (Class I, Grade A)
IV. Operative issues
A. Operative technique
Guideline—The extent of resection of the colon should
correspond to the lymphovascular drainage of the site of the
colon cancer. Level of evidence (Class II, Grade B)
B. Synchronous colon cancer
Guideline—Synchronous colon cancers can be treated by
two separate resections or subtotal colectomy. Level of evidence (Class II, Grade B)
C. Contiguous organ attachment
Guideline—Colon cancers adherent to adjacent structures
should be resected en bloc. Level of evidence (Class II,
Grade A)
D. Synchronous resection of liver metastases
Guideline—Resection of synchronous liver metastases
may be reasonable to perform at the time of the initial colon
resection. Level of evidence (Class III, Grade B)
E. Role of oophorectomy
Guideline—Bilateral oophorectomy is advised when one
or both ovaries are grossly abnormal or involved with contiguous extension of the colon cancer. However, prophylactic
oophorectomy is not recommended. Level of evidence (Class
II, Grade B)
F. Role of laparoscopic resection
Guideline—Relative merits of laparoscopic versus open
resection for colon cancer remain unproved at this time. Level
of evidence (Class II, Grade B)
V. Operative issues—emergent
A. Obstructing colon cancer
402 A.J. Senagore and R. Fry
Guideline—Patients with an obstructing right or transverse
colon cancer should undergo a right or extended right colectomy. A primary ileocolic anastomosis can be performed in
the appropriate clinical setting. Level of evidence (Class II,
Grade C)
Guideline—For the patient with a left-sided colonic
obstruction, the procedure selected should be individualized
from a variety of appropriate operative approaches. Level of
evidence (Class II, Grade C)
B. Colonic perforation
Guidelines—The site of a colonic perforation caused by
colon cancer should be resected, if at all possible. Level of
evidence (Class III, Grade C)
C. Massive colonic bleeding
Guideline—Acutely bleeding colon cancers that require
emergent resection should be removed following the same
principles as in elective resection. Level of evidence (Class
III, Grade C)
VI. Staging of colon cancer
Guideline—Colon cancers should be staged using the TNM
staging system. Level of evidence (Class II, Grade B)
Guideline—To be properly evaluated, one should strive to
have a minimum of 15 lymph nodes examined microscopically. Level of evidence (Class II, Grade B)
VII. Adjuvant therapy
A. Chemotherapy
Guideline—Postoperative adjuvant systemic chemotherapy
has a proven benefit in Stage III colon cancer and may be beneficial in certain high-risk Stage II patients. Level of evidence
(Class I, Grade A)
B. Immunotherapy
Guideline—The value of immunotherapy for colon cancer
is undetermined. Its use is recommended within the setting of
a clinical trial. Level of evidence (Class II, Grade C)
C. Intraperitoneal/Intraportal Chemotherapy
Guideline—Intraperitoneal and intraportal infusions of
chemotherapy are recommended only in the confines of a
clinical trial. Level of evidence (Class II, Grade C)
D. Radiation therapy
Guideline—The role for radiation therapy in colon cancer
is limited. Level of evidence (Class II, Grade C)
Reprinted from Dis Colon Rectum 2004;47:1269–1284.
Copyright © 2004. All rights reserved. American Society of
Colon and Rectal Surgeons.
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29
The Preoperative Staging of Rectal Cancer
Jonathan E. Efron and Juan J. Nogueras
The classification of cancers of the rectum into a staging system with both therapeutic and prognostic applications has
been the goal of pathologists and clinicians for the greater
part of the last century. Different staging systems for colorectal cancer are in use today; however, the majority are modifications of a common framework using similar nomenclature
with the unfortunate results of inconsistencies and confusion.
Most staging systems rely on examination of the pathologic
specimen as well as information gained during surgery. Thus,
they are useful only in the postoperative setting and have little use for the purpose of preoperative therapy. Cuthbert
1
Dukes
category of the case before operating, this would be very useful information.” As the therapeutic options available for the
treatment of rectal cancer increase, the ability to accurately
stage a rectal tumor preoperatively takes on greater importance. Accurate and reproducible preoperative staging provides uniformity among numerous investigative centers;
specifically those involved in adjuvant preoperative therapy
trials. Finally, the ability to stage the tumor preoperatively
permits the physician to convey more accurate information to
the patient and the family with regard to therapeutic options
and prognosis.
are most useful in the preoperative staging of rectal cancers
include the depth of penetration of the tumor through the rectal wall, the presence or absence of metastasis to the regional
lymph nodes, and the presence of distant metastases.
Clinicians have a variety of diagnostic tools at their disposal
that can aid in delineating these aforementioned factors. The
most frequently used modalities for the preoperative staging
of rectal tumors available today are clinical examination,
computed tomography (CT), magnetic resonance imaging
(MRI), endorectal ultrasonography (ERUS), and positron
emission tomography (PET).
tial evaluations are ordered. Laboratory tests including CEA
declared in 1932 “if it would be possible to decide the
The tumor-related factors of prognostic significance that
At the time of history and physical examination, other ini-
(carcinoembryonic antigen) levels and liver function tests
may also provide useful information in patients with rectal
cancer. There is a small risk of metastatic spread of rectal cancer to the lung, bypassing the liver, therefore a baseline chest
X-ray should also be obtained.
Clinical Evaluation
Because of its anatomic location, clinical examination of the
rectum can be performed with minimal discomfort to the
patient. Careful digital assessment of the rectal tumor may
yield valuable information. Table 29-1 lists some of the
important parameters that should be recorded during the
physical examination of a rectal tumor. A clinical staging
system based on tumor mobility was first established by
York-Mason
this clinical staging system, tumor mobility is correlated with
the level of tumor penetration in the different layers of the
rectal wall (Table 29-2). Nicholls et al.
cal staging system and discovered that senior examiners had
an 80% accuracy in distinguishing CS1 and CS2 tumors from
CS3 and CS4 tumors, but only a 50% accuracy in detecting
lymph node metastasis. The accuracy was directly proportional to the experience of the examiner. Factors that facilitated clinical assessment were the number of quadrants
involved, the mobility of the tumor, and palpable extrarectal
growths. This study clearly showed that useful information
can be obtained from digital examination of rectal tumors.
However, certain limitations of a digital examination must be
recognized. The accurate assessment of early invasion into
the rectal wall has been disappointing, especially in selecting
patients for local excision of such a tumor. Clinical staging is
more accurate in correctly assessing the stage of more
advanced lesions where local excision is not an option.
Finally, only tumors of the mid and distal rectum can be
assessed by digital examination.
2
in 1976 and subsequently modified in 1982.3In
3
evaluated this clini-
405
406 J.E. Efron and J.J. Nogueras
TABLE 29-1. Tumor characteristics to assess on digital examination
Location
Morphology
Number of quadrants involved
Degree of fixation
Mobility
Extrarectal growths
Direct continuity
Separate
TABLE 29-2. Clinical staging system
Clinical stage Mobility (level of invasion)
CS1 Freely mobile Submucosa
CS2 Mobile with rectal wall Muscularis propria
CS3 Tethered mobility Perirectal fat
CS4 Fixed/tethered fixation Adjacent tissues
Pathologic correlation
Local and Regional Staging
CT Scan
CT scan is helpful in providing an image of the entire pelvis
and the relationship of the tumor to surrounding pelvic structures especially for advanced tumors. However, CT scan has
not proven to be very accurate in determining the depth of
penetration of the tumor through rectal wall or assessing
involved perirectal lymph node metastasis.
Table 29-3 summarizes the results of several studies in
which CT scan was used to delineate the penetration of the
tumor through the rectal wall and the presence or absence of
involved perirectal lymphadenopathy.
The reported accuracy rate of CT scan in determining tumor
penetration through the rectal wall ranges from 52% to 100%.
CT scan is unable to depict the layers of the rectal wall. Thus,
for tumors that are confined to the rectal wall, CT scan cannot
distinguish tumors that are confined to the submucosa from
those that have breached the submucosa and involve the muscularis propria. In cases of advanced tumor growth, CT scan
ABLE 29-3. Accuracy of CT scan in preoperative staging of rectal
T
cancer
No. of T staging N staging
patients (%) (%)
Dixon et al., 1981
Grabbe et al., 1983
Freeny et al., 1986
Thompson et al., 1986
Holdsworth et al., 1988
Goldman et al., 1991
Zerhouni et al., 1996
Matsuoka et al., 2002
Chiesura-Corona et al., 2001
Harewood et al., 2002
4
5
7
6
8
9
10
11
12
13
4–13
47 78 49
54 79 56
80 62 35
25 70 35
17 94 70
30 52 64
365 74 62
20 100 70
105 82 79
80 71 76
does provides valuable information about the relationship of
the tumor to the surrounding viscera and pelvic structures.
The accuracy of CT scan in determining lymph node
involvement ranges from 35% to 70%. One drawback of CT
scan is its inability to detect lymph nodes smaller than its
resolution threshold of 1 cm. A second drawback of CT scan
for the assessment of perirectal lymph node metastasis is its
inability to differentiate between tumor metastasis and
inflammation in enlarged lymph nodes.
New technology such as the multidetector-row CT
(MDRCT) may significantly improve the ability of CT scans
to accurately determine the depth of invasion and lymph node
metastasis in rectal cancer. MDRCT utilizes four detectors
which result in a much higher resolution and better multipla-
14
nar reformation of the images. Matsuoka et al.
compared 21
patients who had MDRCT with 21 patients that had MRI
evaluations of the pelvis for rectal cancer. They reported an
accuracy rate of 95% on depth of invasion for MDRCT versus 100% for MRI, whereas lymph node accuracy was 70%
versus 61% for MDRCT and MRI, respectively.
Magnetic Resonance Imaging
MRI is a relatively new modality for the staging of rectal cancer. Since its original description in 1986,
have compared the accuracy of MRI in staging rectal cancers
with other imaging modalities such as CT scan and ERUS.
Accuracy rates for MRI in the preoperative staging of rectal
cancer have varied according to technique.
The traditional body coil MRI studies have ranged in accu-
racy from 55% to 95%.
15–35
The addition of an endorectal coil
to this technique resulted in T stage accuracy rates of
66%–91%.
Kim et al.,
17,30,32,33,36
27
in the largest published trial to date examining
These results are listed in Table 29-4.
the accuracy of MRI staging of rectal cancer, compared the
histopathologic staging with the preoperative staging in 217
patients. The accuracy for the depth of invasion was 81% and
for regional lymph node metastasis was 63%. Their technique
involved injection of intravenous contrast material and examining T1-weighted spin-echo images and T2-weighted turbo
spin-echo images. Brown et al.
28
examined preoperative prognostic factors in 98 patients with rectal cancer using high-resolution MRI with a thin section technique. A whole body scan
was performed and only T2 weighted images were examined.
The accuracy rate in assessing the T stage was 94%, for
lymph node involvement was 84%. In their article, Brown
28
et al.
introduced new criteria to define MRI T staging (Table
29-5). MRI identification of metastatic lymph node involvement has not been standardized, which may explain the great
variation in accuracy. Kim et al.
involvement if they demonstrated heterogeneous texture,
irregular margins, or were enlarged to greater than 10 mm.
However, Brown et al.
36
demonstrated that lymph node size
was not an accurate predictor of metastatic disease and, therefore, they relied on mixed signal intensity and irregular or
15,16
multiple studies
27
considered lymph node
29. The Preoperative Staging of Rectal Cancer 407
TABLE 29-4. Accuracy of MRI in the preoperative staging of rectal cancer
Year No. of patients T staging (%) N staging (%)
de Lange et al.
Chan et al.
Okizuka et al.
Thaler et al.
Schnall et al.
Joosten et al.
Indinnimeo et al.
Hadfield et al.
Zagoria et al.
Kim et al.
Gagliardi et al.
Brown et al.
Low et al.
*
Endorectal coil used in MRI.
18
17*
21
25
30*
32*
34*
35
33*
27
29
28
31
1990 29 89 65
1991 12 91 75
1993 33 88 88
1994 34 82 60
1994 36 81 72
1995 15 66
1996 23 78 79
1997 38 55 76
1995 10 80
2000 217 81 63
2002 28 86 69
2003 94 85 84
2003 48 85 68
ill-defined borders of the lymph nodes. Further studies need
to be performed to determine the accurate predictors of lymph
node metastasis on MRI.
In recent years, tumor involvement of the circumferential
resection margin (CRM) has been identified as an important
predictor of locoregional recurrence in rectal cancer patients
undergoing a radical proctectomy with total mesorectal excision (TME).
37–40
Postoperative radiation is not effective in
reducing the risk of local recurrence in patients with a positive
41
CRM,
and a curative operation in these patients will require
either tumor downstaging by preoperative chemoradion, an
extended resection, or both. Consequently, the preoperative
assessment of the relationship of the tumor with the fascia propria of the rectum, the CRM in patients treated with TME, has
become of utmost importance in deciding the type of neoadjuvant therapy and planning the surgical resection. The fascia
propria of the rectum is well visualized by phased-array coil or
endorectal coil MRI and several studies have suggested that
MRI can predict with high degree of accuracy the distance of
the tumor to the fascia propria of the rectum.
42–44
Furthermore,
because of its multiplanar capabilities, MRI is the most accurate imaging technique in assessing the relationship of the
tumor with the levator plate and the sphincter complex. This
information may be useful in selecting patients with low rectal
TABLE 29-5. MRI T staging as proposed by Brown et al.
MRI T stage
T1: Low signal in the submucosal layer or replacement of the submucosal
layer by abnormal signal not extending into circular muscle layer.
T2: Intermediate signal intensity within muscularis propria. Outer muscle
coat replaced by tumor of intermediate signal intensity that does not extend
beyond the outer rectal muscle into perirectal fat.
T3: Broad-based bulge or nodular projection (not fine speculation) of inter-
mediate signal intensity projecting beyond outer muscle coat.
T4: Extension of abnormal signal into adjacent organ; extension of tumor sig-
nal through the peritoneal reflection.
28
Source: Brown et al.
Reproduced with permission from John Wiley & Sons Ltd. on behalf of the
BJSS Ltd.
Copyright British Journal of Surgery Society Ltd.
28
cancer for a sphincter-saving procedure. Therefore, MRI with
a surface coil provides useful information in patients with
locally advanced rectal cancer.
Endorectal Ultrasound
Recently, there has been much interest in the technique of
ERUS for the preoperative staging of rectal tumors. This
approach is proving to be safe, reliable, and relatively inexpensive. It is an outpatient procedure requiring only enema
preparation and no sedation or anesthesia. The frequency of
the ultrasound transducer determines its focal range and ultrasonographic resolution. Complete circular imaging of the rectal wall can be obtained with the 360-degree rotating
endorectal probe. Most investigators are now using a 7.0- or a
10-mHz transducer which provides a five-layer anatomic
model of the rectal wall with three hyperechoic circles and two
hypoechoic concentric circles (see Chapter 7).
and Feifel
46,47
proposed a preoperative staging classification
based on the ultrasonographically determined depth of penetration to the TMN classification system (see Chapter 7).
Table 29-6 lists the results of ERUS in the preoperative
staging of rectal cancer.
9,13,25,47–57
The accuracy of the ultrasound in determining the depth of penetration of the tumor
through the layers of the rectal wall varied from 60% to 93%.
As with all modalities, there is a significant learning curve
associated with the interpretation of the ERUS image. Orrom
51
et al.
at the University of Minnesota demonstrated an accuracy of 75% in the overall group; however, when they looked
at their last 6 months of the study, the authors showed an
improvement with a 95% accuracy in determining depth of
invasion. Overall, 5% of the tumors were overstaged. This
tendency to overstage tumors was a common finding throughout this series because of the inability to differentiate perirectal inflammation from tumor infiltration in the perirectal fat.
Orrom et al. also point out some of the pitfalls in performing
this examination.
51
These authors routinely use a proctoscope
to introduce the ultrasound probe, thereby ensuring that a
45
Hildebrandt
408 J.E. Efron and J.J. Nogueras
T
ABLE 29-6. Accuracy of ERUS in preoperative staging of rectal
cancer
No. of T staging N staging
patients (%) (%)
Hildebrandt and Feifel, 1990
Beynon et al., 1989
Jochem et al., 1990
Milson et al., 1990
Orrom et al., 1990
Goldman et al., 1991
Thaler et al., 1994
Starck et al., 1995
Nielsen et al., 1996
Massari et al., 1998
Harewood et al., 2002
Garcia-Aguilar et al., 2002
Marusch et al., 2002
Hull et al., 2004
48
49
50
51
9
25
52
53
54
13
56
57
47
55
137 88 73
100 93 83
50 80 72
52 83 70
77 75 82
32 81 68
37 88 80
34 88 71
100 85 66
75 91 76
80 91 82
545 69 64
422 63 —
411 60 —
visible nodes are considered pathologic. However, ERUS
cannot differentiate between inflammatory or neoplastic
59
nodes. Hildebrandt et al.
have described different echogenic
parameters in nodes that were replaced by tumor as compared with inflammatory lymph nodes. They determined that
hypoechoic lymph nodes represented tumor metastases
whereas hyperechoic lymph nodes represented inflammatory
changes. They reported an overall accuracy rate of 78% and
they attributed their errors to micrometastases, mixed lymph
nodes, and changing echo patterns within inflammatory
nodes.
Andersson and Aus
60
reported a case in which a transrectal
ultrasound–guided biopsy of a hypoechoic perirectal lymph
node was performed in order to verify metastatic growth in a
patient who had already undergone a local excision of a rectal cancer. Harewood et al.
13
investigated the impact of ERUSguided fine-needle aspiration of perirectal nodes in the
preoperative staging of 80 consecutive patients with rectal
complete image of the tumor is obtained. This eliminates the
possibility of error in the situation whereby a tumor is less
invasive distally and more invasive proximally. A blind insertion of the endorectal probe has the potential to inadequately
visualize the entire tumor and miss a proximal level of deeper
invasion.
A longer-term follow-up of the Minnesota series was pub-
lished in 2002 by Garcia-Aguilar et al.
55
These investigators
reported their experience with 1184 patients with rectal carcinoma or villous adenoma that underwent endorectal ultrasonography. Histopathologic correlation was available for the
545 patients who had no prior radiotherapy. The accuracy of
ERUS in assessing level of penetration was 69%, with 18%
overstaged and 13% understaged. The accuracy for nodal
involvement in the 238 patients who had radical surgery was
64% with 25% overstaged and 11% understaged. The overall
accuracy in this large series is lower than previously reported.
However, in this series, patients with locally advanced tumors
that received preoperative radiation were eliminated from the
analysis. The accuracy was higher for benign lesions, and for
full-thickness lesions. Lower accuracy rates occurred for T1
and T2 lesions.
Preoperative radiation of rectal cancer causes various
degrees of tumor regression resulting in scarring and fibrosis
that impairs ultrasound imaging interpretation. Napoleon
58
et al.
examined the results in determining depth of wall invasion in patients who had received radiotherapy and compared
them with a group of patients with no previous radiotherapy.
These authors determined that depth of wall invasion was correctly determined in 86% of patients without radiotherapy, but
cancer. In this series, fine-needle aspiration did not significantly improve nodal staging over ERUS.
13
Based on these
results, and the potential risk of spreading cancer cells into the
mesorectum in patients with metastatic lymph nodes, ultrasound-guided biopsy of enlarged perirectal nodes is not routinely used in clinical practice.
Several prospective studies have compared ERUS and MRI
in the preoperative staging of rectal cancer. Surface coil MRI
is less accurate than ERUS in assessing rectal wall invasion
and is primarily used for the staging of locally advanced rectal cancers. MRI with endorectal coil allows visualization of
the different layers of the rectal wall, and can potentially be
used for the preoperative staging of early rectal cancers.
Kwok et al.
61
performed a systematic review of the literature
to compare the accuracy of several imaging techniques in the
preoperative staging of rectal cancer. They concluded that
ERUS has the highest sensitivity and specificity in assessing
wall penetration, but MRI with endorectal coil had higher
accuracy than ERUS in assessing nodal metastasis. However,
MRI with endorectal coil is cumbersome to the patient, technically difficult, and not widely available.
Three-dimensional ultrasound is a new technique that has
recently been developed. Kim et al.
62
compared the accuracy
of conventional ultrasound to three-dimensional ultrasound in
the staging of rectal cancer. They found no significant difference in accuracy of either depth of invasion or lymph node
metastasis. Their study was small and there was a trend to
higher accuracy with the three-dimensional ultrasound.
Further investigation is required for the evaluation of threedimensional ultrasound on rectal cancer staging.
in only 47% of those patients in whom previous radiotherapy
had been administered. Therefore, endorectal ultrasonography should be performed in the patient before receiving radio-
Distant Metastases
therapy in order to increase its accuracy rate.
The accuracy in determining lymph node involvement
with the ERUS varies from 68% to 83% (Table 29-6).
Normal mesorectal nodes are not visualized with ERUS;
The detection of distant metastasis is of prime importance for the accurate staging of rectal cancer. The most
common site of distant spread of rectal cancer is the liver.
29. The Preoperative Staging of Rectal Cancer 409
The most frequently used imaging modalities used today to
detect liver metastasis are abdominal ultrasound and CT
scans. MRI and intraoperative ultrasound are now used
with increasing frequency, particularly in patients with
known metastasis that are considered candidates for surgical
resection.
Studies that have investigated the use of preoperative ultrasonography and CT in the detection of liver metastases have
reported an overall accuracy ranging from 66% to 90%.
63–66
Table 29-7 lists some of the results of these earlier studies.
Clarke et al.
67
investigated the accuracy on intraoperative
ultrasonography in detecting liver metastasis according to
their location by anatomic liver segments. Both techniques
were similar in detecting liver metastasis except for lesions
located in the lateral segment of the left lobe of the liver
where preoperative ultrasonography was accurate (76%) compared with CT scan (29%). The lower resolution of CT scan
in the left lateral segment lesions was attributed to artifacts
from the stomach and cardiac motion.
Ward et al.
68
from the National Institute of Health reported
the results of a study evaluating preoperative CT with various
enhancement techniques and MRI of the liver. All patients
eventually underwent laparotomy with intraoperative ultrasonography in some cases. Correlation of the imaging techniques with surgical findings was performed to determine the
specificity and sensitivity of each test. The authors concluded
that the MRI examination had the lowest false-positive rate
and proved to be the best hepatic imaging study in the detection of colorectal metastases.
Despite refinements in enhancement techniques of CT
and external ultrasounds, along with the addition of MRI, the
resolution threshold for liver metastases remains at approximately 1 cm. For lesions in the left lateral segment of the liver,
this threshold is larger. Even after preoperative imaging, up to
one-third of colorectal cancer patients are found at the time of
surgery to have unsuspected additional liver lesions or extrahepatic metastases. Other modalities used to detect metastatic
disease not seen with conventional imaging techniques are
PET scan and radioimmunoscintigraphy.
PET scans have been shown to have higher sensitivity and
specificity in detecting recurrent rectal cancer than both CT
and MRI.
70–73
Although sensitivity and specificity in diagnosing tumor recurrence are higher for PET scans, its spacial
resolution is not very accurate and therefore other studies
such as MRI and/or CT scans are required to define the
precise location of the tumor to important anatomic
landmarks. Current scanners are available that fuse CT or MR
images with the PET scan images. The ability of these fused
images to increase sensitivity or specificity is being investi-
74
gated. Cohade et al.
compared PET scan and PET/CT
images in a series of 45 patients with colorectal cancer. They
found that the overall staging accuracy increased from 78% to
89% with PET/CT. PET scans when coupled with other studies are also being used to assess the extent of pathologic
response of rectal cancers that receive neoadjuvant ther-
75,76
apy.
Further studies are required on this use of PET scans
before any definitive conclusions can be drawn.
The impact of PET in the preoperative staging and man-
agement of rectal cancer patients has been studied by Heriot
77
et al.
in a series of 46 patients who were assessed with PET
scans at the time of their initial diagnosis. The surgical management was changed for 17% of the patients because of positive PET scan findings that upstaged the disease. These
changes in management included canceling surgery and
changing the field of administered radiation.
At the present time, PET scan is primarily used for the
diagnosis of local and distant recurrence after curative surgery
for colorectal cancer. It is also being used with increased frequency to detect distant metastasis of the time of the primary
diagnosis of rectal cancer.
Immunoscintigraphy refers to the use of radiolabeled monoclonal antibodies that bind specifically to tumors to aid in
detection and diagnosis. Most studies have primarily examined patients with colon cancer or either colon and rectal can-
69
cer. Few have examined primarily rectal cancer. The clinical
application of this technique has been limited. Different monoclonal antibodies have been used, making it difficult to compare studies. The accuracy rate of immunoscintigraphy in
detecting primary or metastatic colorectal cancers ranges
from 63% to 96%.
78–85
There has not been a defined role for the use of preoperative or intraoperative radiolabeled immunoscintigraphy when
dealing with a primary rectal cancer. Likewise, its role in
management of recurrent rectal cancer has yet to be well
defined. Intraoperatively, it may enhance the surgeon’s ability
to assess both local and metastatic spread.
Conclusion
T
ABLE 29-7. Accuracy of ultrasound and CT scan in the preoperative
diagnosis of liver metastasis from colorectal cancer
Ultrasound (%) CT (%)
Sheur et al., 1985
Gunven et al., 1985
Castaing et al., 1986
Gozzetti et al., 1986
63
64
65
66
90 85
66 80
68 74
80 74
The accurate preoperative tumor staging is essential to select
the best therapy for the rectal cancer patient. Presently, the
depth of invasion and evidence of perirectal lymph node
involvement is best assessed with ERUS. Abdominal and
pelvic CT scanning or MRI are also important to detect
extrarectal tumor spread and liver metastasis. A chest X-ray is
also important to exclude pulmonary metastasis. The role of
new imaging modalities such as PET in the staging of rectal
cancer patients is currently under investigation.
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