Nov 26, 1985 - to be accurate in staging patients with primary rectal or rectosigmoid carcinoma .... pouch. Four patients had squamous cell lesions of the anorectal region ..... proven uterine fibroid) that could not be separated from the rectum.
703
Preoperative Postoperative Rectosigmoid
William Robert William
M. Thompson1 A. Halvorsen1 L. Foster, Jr.1 Leroy Roberts1 Rebecca Gibbons2
and CT Staging Carcinoma
of
This study reports a 4 year experience using CT for preoperative staging and for evaluation of patients with rectal and sigmoid carcinoma after surgery. All patients were evaluated on a GE 8800 scanner using 1 cm contiguous slices. Only 15 of the 25 preoperative patients were staged correctly. The other 10 patients were understaged by CT. The accuracy of detecting local invasion was 70%, but only seven (35%) of 20 patients had accurate assessment of lymph nodes. The overall accuracy of CT staging in the 46 postoperative patients was 87%, with a sensitivity of 91% and a specificity of 72%. Most recurrences
were found in the pelvis;
16 patients
had liver metastases,
and
metastatic disease obstructing the ureters was detected in eight patients. On the basis of these results, it was concluded that CT should not be used routinely to preoperatively stage patients with rectosigmoid carcinoma. However, all patients who have undergone resection for rectal or sigmoid carcinoma should have aggressive CT evaluation including a baseline study at 2-4 months and then follow-up studies at every 6 months for at least 2 years. All new or enlarging masses should have CT-guided biopsies. This approach may prolong survival by detecting early asymptomatic recurrences.
Computed tomography (CT) is a recognized method for pre- and postoperative staging of rectal carcinoma [1 -1 0]. Initially CT was reported to be accurate staging
patients
with
primary
rectal
or
rectosigmoid
carcinoma
[1 -5].
in
In 1983
Grabbe et al. [6] demonstrated in 1 55 patients that, while preoperative CT was more accurate than the clinical staging scheme of Mason [1 1 ], routine staging by CT is not justified because slight perirectal tumor spread and lymph node metastases cannot be accurately predicted. Recently, the conclusions of Grabbe et al. were confirmed by Adalsteinsson et al. [1 0] in 1 54 patients. CT is perhaps more valuable in the detection and/or staging of pelvic abnormalities in patients who have had resection of rectal or rectosigmoid carcinoma [2, 1 2-20]. While postoperative changes such as fibrosis, hematoma, and abscess can mimic tumor recurrence [21 ], usually these can be distinguished by performing baseline CT within 2-4 months of resection and then at 6 month intervals [21]. CT-guided percutaneous biopsies should be performed of all suspicious masses [18, 19]. Received September 16. 1985: accepted November 26, 1985.
after
revision
Presented in part American Roentgen 1985.
at the annual Ray Society,
meeting Boston,
of the April
‘Department of Radiology. Veterans Administration Hospital, and Duke University Medical Center, Box 3808. Durham, NC 27710. Address reprint requests to W. M. Thompson. 2
Present address: 1058 Cherryfield Ave. 3, Wor-
thington, AJR
Materials
April
1986
0361 -803x/86/1 464-0703 C American Roentgen Ray Society
the
From
and February
or rectosigmoid recurrence.
OH 43085.
146:703-710,
During
past
4 years
evaluation of patients purpose of this study
we
have
used
CT
for
preoperative
staging
and
with rectal and rectosigmoid carcinoma after surgery. is to report our results in these two groups of patients.
for
The
Methods 1980 to June
carcinoma
The studies
1985 71 patients
underwent
were performed
(25 pro- and 46 postoperative)
CT for staging of the primary
with rectal
tumor or detection
of
on a GE CT/T 8800 whole-body scanner. The scans were obtained from the dome of the liver to the anal verge at 1 cm intervals. At 2-6 hr before the examination, 400-500 ml of 1% methylglucamine diatrizoate (Gastrografin, Squibb) or 1% barium (E-Z CAT, E-Z-EM) was given orally. Rectal contrast material (200-300 ml) was
THOMPSON
704
ET AL.
used
only
filled
by
AJR:146,Apnl
in isolated the
oral
(methylglucamine selected cases. The medical, patient
were
documented clinical studies
surgical,
when
Aenografin,
pathologic,
the rectum
Intravenous
Squibb)
and radiologic
injected
records
in
of each
by surgery,
percutaneous needle biopsy, or compelling CT reports were used to determine the prowhile a retrospective evaluation of the CT
also
performed.
To
determine
stage
was
poorly material
in all cases
The
the clinical
was
contrast
reviewed.
CT accuracy, was
primarily material.
diatrizoate,
evidence.
spective
cases
contrast
1986
the
of the tumor
stage,
was
all CT
scans
were analyzed for the presence of a tumor mass, extension beyond the bowel wall, involvement of adjacent organs, enlarged lymph nodes (>1 .5 cm), and metastases to distant sites. The modified Dukes staging system [22-26] was compared with the University of California, San Francisco, CT staging system reported by Thoeni et al. (3] and Moss et al. 117].
Preoperative
Evaluation
Twenty-five
male
patients
with
biopsy
evidence
of rectal
cancer
were evaluated by CT. Each of these patients had a mass larger than 1 .5 cm shown by barium enema. In five patients with massive tumors longer than 8 cm, CT was done primarily to plan radiation therapy as the tumors were either perforated or considered too large for primary resection. Fig. 1.-True negative for invasion: stage II. Large asymmetric posterior wall thickening without evidence of invasion into perirectal fat (stage II, Dukes A) was confirmed at operation and by pathology. However, 30 of 38 lymph nodes contained tumor. None of these were demonstrated by CT. Also, patient had multiple small calcified densities in liver on CT. proven to be
multiple metastases. Dukes D.
Fig.
tumor.
Recurrent Forty-six
Thus, this patient had a stage IV,
2.-True-positive
Increased density (arrows) indicating tumor
for rectal
invasion.
A,
in perirectal extension
Stage
lilA. Large circumferential
fat and in area of left perirectal through bowel wall. Ten of 15
These
patients
had
a palliative
operative staging. In the other 20 patients was performed to supplement preoperative
rectal fascia nodes
contained tumor not detected by CT, a Dukes C lesion. B, Huge circumferential rectosigmoid tumor invading bladder (arrow) and extending posterior to sacrum
(arrowhead).
Rectosigmoid
colostomy
with smaller tumors, clinical staging.
and
CT
Carcinoma
patients (45 men and one woman) had undergone surgery or rectosigmoid malignancies. Twenty-seven patients had
c, Stage IlIB. Large circumferential material in lumen (arrow). Extension pelvic side wall (single arrowhead) (arrowheads). Tumor unresectable at operation. contrast posterior
diverting
tumor through and into
with small amount of perirectai fat to left left seminal vessicle
CT
AJA:146, April 1986
OF
RECTOSIGMOID
CARCINOMA
Fig. 3.-False-positive invasion. A, Large circumferential tumor with marked iocrease in density of penrectal fat and thickening of periroctal fascia (long arrows), called a Stage lIlA tumor but at operation and on pathologic examination tumor confined to rectal wall. No explanation given for tcreased perirectal soft-tissue density. One of 12 lymph nodes positive for tumor. No abnormal nodes noted on CT; probable normal-size node (short arrow). B, Smafi tumor mass posterior to rectal contrast material. Tumor was diagnosed as invading levator ani (arrows), but at operation no evidence of invasion could be found. Uver metastases were detected by CT (stage IV).
abdominoperineal
resections,
13 had
anterior
resections
with
a rec-
tosigmoid anastomosis, three had local resections, and three patients had only colostomies with creation of a Hartman pouch. Four patients had squamous cell lesions of the anorectal region; the other 42 had adenocarcinomas of the rectum or rectosigmoid colon. The interval between surgery and CT averaged 14.5 months (range, 1-60 months). A total of 70 scans was obtained in the 46 patients with 16 of the patients having multiple scans.
Results Preoperative
705
Fig. 4.-False-negative invasion. Circumferential tumor at rectosigmoid junction. No evidence of vivasian detected by CT, but at operation and on pathologic examination tumorextended through bowel waN into perirectal fat (stage lIlA). One of three distant lymph nodes contained tumor(Dukes C). No enlarged nodes detected by CT, but small densities (arrows) adjacent to rectum are probably nodes.
dence of invasion (fig. 1), and 1 6 had abnormal perirectal fat with evidence of tumor extension (fig. 2A). Nine patients had CT findings of invasion of a contiguous structure: three to bladder (fig. 2B), one to prostate, two to pelvic side wall musculature (fig. 2C), and two to sacrum (fig. 2B). Metastatic disease to the liver was detected in seven patients and to the lymph nodes in four. Metastases to the spleen, right ureter, and malignant ascites were each detected in a single patient. The CT results for detecting invasion or extension and abnormal lymph nodes are shown in table 1 The overall accuracy for invasion was 70%; the specificity was only 57%. Three false positives occurred in patients who by CT criteria had extension into the perirectal fat and/or the levator ani (fig. 3) (stage lIlA), but the tumor was confined to the rectal wail (a stage II). These patients had positive lymph nodes (Dukes C). Since most of the 1 7 patients with metastatic lymph adenopathy had normal-size nodes, CT did very poorly in detecting metastases to lymph nodes (sensitivity, 22%) (table 2). Retrospective review of the CT scans yielded two (8%) of 25 patients whose scans were not initially interpreted correctly. In one tumor extension to the sacrum was not described, and in another extension to the pelvic side walls was present and not described in the report. Table 2 shows the results comparing the modified Dukes .
Evaluation
Twenty-one of the 25 patients had rectal carcinoma and four had sigmoid tumors. The mean age of the patients was 56 years (range, 33-75 years). The presenting symptoms and/or signs were gastrointestinal bleeding in 1 4, lower abdominal pain in five, constipation in three, diarrhea in two, and weight loss in one. Two patients had normal CT scans. A rectal or rectosigmoid mass was detected in 22 (figs. 1-4) and liver metastases were detected in one patient whose CT study was limited to the upper abdomen. The tumor involved the circumference of the bowel in five, the anterior wall of the rectum or sigmoid in eight, the lateral wall in four, and the posterior wall in five. Eight of the patients had normal perirectal fat without evi-
THOMPSON
706
staging system [26] with the University of Califomia, San Francisco, CT staging system [3, 17]. Only 15 of the 25 patients were correctly staged. The other 1 0 patients (40%) were understaged by CT (fig. 4). Five were called stage lIlA (Dukes B) with invasion, but all had metastatic nodes at surgery not detected by CT (Dukes C). Four patients had no CT evidence of invasion (Stage II) (Dukes A), but all had metastatic lymph nodes (Dukes C) not detected by CT. One patient who had a thick rectal wall with a normal liver on CT (stage II) (Dukes A) had tiny 6 mm liver and peritoneal metastases at surgery (Dukes 0). Recurrent
Carcinoma
Thirty-five sigmoid
TABLE
of the
46 patients
had recurrent
Twenty-six
patients
carcinoma.
1
: CT Results
Metastases
in Determining Invasion Lymphadenopathy
of true
rectal
or recto-
histologic
confir-
invasion or Extension (n = 24)
positives
No. of true negatives No. of false positives No. of false % Sensitivity % Specificity
negatives .
.
% Accuracy
4
4 3
3 1
4 77 57
12 22 75
70
35
AJR:146, April 1986
of recurrent tumor and nine had clear evidence of recurrence by a compelling clinical examination and
clinical course. recurrent tumor. tasis
on CT
ography.
Fig. 5.-A, tumor
Recurrent carcinoma.
resection. in pelvic
and
Tumor lymph
small recurrent presacral percutaneous biopsy.
extends
had
nodes.
tumor
Another
(arrows)
pericolic
fat, confirmed
this
2: Staging
evidence
a proven
of
liver metasby arteri-
postoperative
ab-
Rectosigmoid
with Modified
Carcinoma
Dukes System
by CT
[26]
A
B
C
2* 1’
0 0
0 4t
0 i
lIlA
0
0
St
0
5
IIIB
0
0
4*
0
4
0
0
0
3
0
13
Total .
perineal
clinical
I II
IV
patient 3 years after abdominal and enlarged pelvic lymph node
no
a questionable
to be a hemangioma had
of Primary
CT Stage
at second
proven
patient
had
with
scess, not a recurrence, and one patient had stones causing bilateral hydronephrosis, not recurrent tumor. No recurrence was present in nine patients (2%) and two (4%) had stage lIlA disease. The other 35 (76%) patients with CT evidence of recurrent tumor were stages IIIB and IV (figs. 5, 6, and 7A) (table 3). The overall accuracy for CT staging in the 46 patients as well as in the 70 individual scans were both 87% and the sensitivities were 91 % and 94%, respectively. The specificities were lower in both groups (table
Correctly
Large recurrence at site of anterior resection (arrows) into right
patients
One patient
Another
operation.
8* 9
Total
2 6
8 25
10.
6 months after B, Recurrent
resection. both
(arrowheads),
D
staged: 15.
tlncorrectlystaged:
anterior
Eight
[3, 16] and Comparison
Enlarged 1>1 .5 cm) Lymph Nodes (n = 20)
13
mation tumor
TABLE
or Distant
and Metastatic
No.
had
ET AL.
CT shows proven by
Fig. 6.-Recurrent tumor obstructing CT during needle biopsy of small tumor obstructing left scopic hematuria
Dukes
B sigmoid
ureter. Patient presented 2 years after anterior
cancer.
left ureter. recurrence with microresection of
AJR:146,
CT
April 1986
OF
RECTOSIGMOID
CARCINOMA
707
Fig. 7.-Recurrent carcinoma versus postoperative change. A, Large pelvic soft-tissue mass after abdominal penneal resection. Mass extends from prostate to pelvic side walls. B, Same patient in prone position with biopsy needle in mass. Biopsy revealed recurrent tumor. c, Another patient 3 weeks after
abdominoperitoneal resection. Large soft-tissue mass similar to A. D, 12 months later. Marked resolution
of pelvic
mass
(Cf. B). Mass
caused
by post-
operative change.
3:.-
3). There were three false negatives: two were from metastases in superficial inguinal lymph nodes that, though larger than 1 .5 cm, were not initially reported and the third was from metastases to the right colon and distal small bowel that were not reported in the initial report. There were three false positives in the 46 patients; one from a postoperative pelvic abscess, one small hemangioma called a liver metastasis, and one patient had bilateral hydronephrosis due to stones. Three other baseline scans (in the group of 70) were suspicious for recurrence (fig. 7C), but follow-up CT studies proved
these to be only postoperative abnormalities (fig. 70). Thus, these were included as false positives in the group of 70 scans but not in the 46-patient group (table 3). The recurrent tumors were most often found in the pelvis. Twenty-eight patients had tumor extending to pelvic side walls, prostate, and/or bladder. The liver was involved in 16 patients while recurrent tumor obstructing the ureters was detected in eight (fig. 6). Metastases were detected in both pelvic (13 patients) and extrapelvic (12 patients) lymph nodes (fig. 5B), adrenal glands, and the skeleton.
708
THOMPSON
TABLE
3: CT in Staging
Rectosigmoid
Recurrent Patients
No. of true No. of true No. of false No. of false % Sensitivity % Specificity % Accuracy
positives negatives positives negatives
.
.
.
.
.
.
.
.
(n
=
46)
Carcinoma cT scans (n
=
70)
47 14 6
32 8 3 3
3
91 72 87
94 82 87
ET AL.
Thoeni et al. used a staging system based on the CT findings and compared this with the Dukes classification. They referenced the original Dukes system [22] but used the Tumbull et al. [26] modification and did not include a complete evaluation of lymph nodes. Grabbe et al. [6] and Adalsteinsson et al. [10] are the only workers who have carefully compared CT staging with the surgical results. Our results are similar (table 1).
Preoperative Discussion Staging
Colorectal
Cancer
Perhaps the most confusing aspect of colorectal cancer is the staging of disease. The original Dukes system is simple and easy to use but does not separate patients into prognostic groups accurately enough [22]. He proposed the following system of classification: stage A-tumor limited to the wall of the rectum; stage B-spread by direct extension through extrarectal tissues; stage C-involvement of regional lymph nodes. In 1 949 Kirkland et al. [23] proposed a modification of the Dukes classification in which they distinguished between involvement into but not through the muscularis (designated B1) and involvement through the muscularis (designated B2). Astler and Coller [24] suggested in 1 954 that the Kirkland modification be extended to the Dukes C stage. Four years later Dukes and Bussey [25] proposed that stage C be divided according to the location of the involved nodes: Cl -involved nodes limited to the pericolic region, and C2-involved nodes to the highest point of ligature of the lymphovascular pedicle. In 1 967 Turnbull et al. [26] added another category, stage D, to include cases with not only adjacent organ invasion, but peritoneal seeding of tumor, and distant metastases to liver, lung, and bone. This was the first systematic attempt to segregate these cases from the standard Dukes categories [26]. The only problem with this category is that metastases in distant lymph nodes is not clearly addressed. In an attempt to bring together the great number of variables that may affect survival, the International Union Against Cancer (UICC) [27] and the American Joint Committee for Cancer Staging and End Result Reporting [28] proposed a TNM classification for colon and rectal cancer. Unfortunately many aspects of the TMN classification, which works well with certain tumors, for example, head and neck cancer, do not apply to colon and rectal tumors. For instance, the size of the primary tumor is not significant in staging colon cancer [29]. Some authors believe this system is not worthwhile [29]. No uniformity exists in the reporting of the staging of rectal carcinoma. The Dukes system has been so changed and modified and constantly confused that it is difficult to know to exactly which A, B, or C an author refers [22-29]. This has introduced confusion in the literature. Thoeni et al. [3] recognized that CT cannot distinguish between extension of tumor into
the muscularis
from
those
extending
through
the
serosa,
and CT is less accurate than lymphangiography in assessing lymph node metastases from pelvic tumors. Therefore, the Dukes system cannot be used for CT staging of rectal tumors.
AJR:146, April 1986
Staging
Our results are not as favorable as many of the early reports. Only 1 5 of the 25 patients were correctly staged (table 2). While CT did detect the presence or absence of local invasion with a fairly high degree of accuracy (70%), CT failed to accurately detect metastatic lymphadenopathy (sensitivity, 22%) (table 1). Nine patients, classified as CT stage II or lIlA equivalent to a Dukes A or Dukes B, had metastatic disease in lymph nodes (Dukes C lesions). In one of the first reports on CT for staging rectal carcinoma, Dixon et al. [2] used three nonspecific pathologic criteria to compare with the CT findings. Overall CT was correct in 37 (79%) of 47 patients in terms of local invasion, but CT detected only seven of 1 8 patients with metastatic adenopathy (39% sensitivity). In 1981 , Thoeni et al. [3] reported CT correctly staged 36 of 39 rectosigmoid cancer patients (92% accuracy). They did correlate the CT findings with a modified Dukes system and found a high degree of correlation. However, Thoeni et al. did not describe the CT evaluation of nodal disease. Also most of their patients had advanced disease (24 of 39 were stage C or D), which accounted for the high degree of correlation of the CT and surgical findings. Zaunbauer et al. [4] correctly staged all 1 1 patients using the CT findings compared with the TMN UICC staging system [27]. They are the only authors to report a 1 00% accuracy for detecting lymph node metastases. Van Waes et al. [5] reported correctly staging 1 7 (81 %) of 21 patients correctly using the Thoeni et al. [3] CT staging system. Two patients had the pelvic disease correctly staged as IIIB, but at operation both had small liver metastases not detected by CT (stage IV, Dukes D). In two other patients CT overestimated the stage of the disease: one was staged llIB (bladder invasion) but a stage lIlA tumor found at surgery, and one stage II tumor was actually a stage I (Dukes A). They concluded that CT provided unique information not available through other means, short of surgery. On the basis of this information the mode of treatment was affected in 1 0 patients. In the two largest series, Grabbe et al. [6] and Adalsteinsson et al. [10] both evaluated over 1 50 patients with CT. Grabbe et al. [6] compared their findings with the Dukes [22] and UICC [27] staging classifications, and Adalsteinsson et al. [1 0] used the Astler and Coller [24] modification of Dukes system. In both series the preoperative CT findings of local infiltration of perirectal fat compared with the histopathology revealed accuracy rates of 60%-79%. Analyzing the same cases with respect to lymph node metastases Grabbe et al. found a sensitivity, specificity, and accuracy of 34%, 92%, and 56%, respectively. In most cases the rare CT finding of an enlarged
AJR:146, April 1986
CT
OF
RECTOSIGMOID
lymph node (>1 .5 cm) indicated nodal metastases. Adalsteinsson et al. [1 0] evaluated all identifiable nodes in two groups, less than 5 mm and greater than 6 mm, and found CT could not be used to detect or rule out lymph node metastases. Both of these results are very similar to ours. Grabbe et al. [6] concluded that CT staging is superior to preoperative clinical staging, but routine staging by CT is not justified. Adalsteinsson in demonstrating the
et al. suggest that CT may be useful extent of perirectal extent in selected
cases where resectability is clinically doubtful. On the basis of our results and the above reports, we do not believe that CT should be used routinely to preoperatively stage rectosigmoid cancer. It should be reserved to evaluate patients with suspected extensive disease or a suspected complication of the tumor such as perforation.
Recurrent
Rectosigmoid
Carcinoma
Our results are similar to most authors previous reports [1 2-1 9]. Most of our 46 patients had advanced disease-20 (43%) stage 1116 (Dukes C) and 1 5 (33%) stage IV (Dukes D). CT correctly staged 40 of the 46 patients (87% accuracy). Moss
et al. [1 7] reported
a 95%
accuracy
rate
with
0%
false
negatives and 5% false positives in 39 patients with recurrent rectal carcinomas. One false positive was from a uterine mass (a surgically
proven
uterine
fibroid)
that
could
not be separated
from the rectum. The other was in a patient diagnosed as a stage II recurrence, but multiple biopsies and surgery revealed only fibrosis. The difficulty encountered distinguishing local recurrent rectosigmoid carcinoma from postoperative change (hematoma,
abscess,
fibrosis,
and
normal
pelvic
structures)
has
been described by a number of authors [1 8, 21 , 30, 31] and was encountered in three patients in our series (fig. 7C). While the CT characteristics of the normal postoperative presacral space have been described and differentiated from recurrent tumor, these imaging features on a single CT scan are not totally definitive. Kelvin et al. [21] reported that 60% of the presacral masses caused by postoperative fibrosis tended to diminish in size and become better defined over time (figs. 7C and 7D), 40% of the abnormalities showed no change. Masses caused by recurrent tumor enlarge and become less well defined on serial studies. The results of Kelvin et al. differed from those of Lee et al., who found no abnormal softtissue abnormalities in 1 1 patients without recurrent disease [30]. Reznak et al. reported a prospective series of 1 0 patients with no recurrence in which five patients had essentially normal postoperative CT scans and five had presacral softtissue masses [31 1. The masses tended to diminish in size although some remained unchanged for 28 months. These authors recommend baseline CT scans of the postoperative presacral space to identify postoperative fibrosis so that follow-up
the
minor
changes that may represent early recurrence. Recently et al. [18] described the CT evaluation of 28 patients
scans
at
regular
intervals
can
detect
Butch with
presacral masses after abdominoperineal resection for rectosigmoid cancer. All lesions were biopsied percutaneously. Fifteen (79%) of the 19 solid masses proved to be recurrent
CARCINOMA
709
tumor, while only three of the five lesions with central areas of low density were recurrent carcinoma and none of the four gas-containing
phasize
masses
the necessity
suspicious
presacral
contained
tumor.
of CT-guided or pelvic
These
results
percutaneous
masses
in these
em-
biopsies
of
patients.
McCarthy et al. [1 9] recently reported comparing CT and carcinoembryonic antigen for detecting recurrent rectosigmoid carcinoma in 28 patients. The authors’ results indicate that serial CT with percutaneous CT-guided biopsy is the most sensitive method for detecting recurrent rectosigmoid carcinoma. Recurrent carcinoma confined to the pelvis occurs in 30%50% of patients after resection of rectosigmoid carcinoma [32]. Isolated pelvic recurrence is a major cause of death in these patients. Over 80% of recurrent pelvic tumors occur within 2 years [32]. On the basis of these facts, prior reports [1 3-1 9], and our findings (table 3), we believe that all patients who have undergone resection for rectal or sigmoid carcinoma should have a baseline CT study 2-4 months after surgery and then every 6 months for 2 years. CT should then be performed at yearly intervals. Any new or enlarging presacral mass or enlarged lymph node not present on a prior study should undergo a CT-guided biopsy. By following such a protocol, early asymptomatic recurrences should be detected and treated appropriately. This approach may prolong survival
in these
patients.
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of
carcinoma
tomography
of colon
BC, et al. Pro-operative of
the
rectum.
Br
carci-
computed J
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1981;54:655-659
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and
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1983;1 49:241-246
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McCarthy SM, Barnes D, Deveney K, Moss AA, Goldberg HI. Detection of recurrent rectosigmoid carcinoma: prospective evaluation of CT and clinical factors. AJR 1985;144:577-579. Kelvin FM, Korobkin M, Breiman RS, et al. Recurrent rectal carcinoma in an asymptomatic patient. J Comput Assist Tomogr 1982;6: 186-188 Kelvin FM, Korobkin M, Heaston DK, Grant JP, Akwari 0. The pelvis after surgery for rectal carcinoma: serial CT observations with emphasis on nonneoplastic features. AJR 1983;i41 :959964
ET
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AL.
Dukes
CE. The classification
of cancer
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April1986
of the rectum.
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