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119
9 Colorectal Cancer Screening and Surveillance
9.17.2 MYH-Associated Polyposis
This is a relatively newly described recessively inherited adenomatous polyposis
syndrome, due to mutations in the MUTYH genes, which overlaps to some degree
with FAP, although it does tend to be milder. Overall though, surveillance and man-
agement recommendations are similar to FAP, with the exception that some patients
with a mild phenotype can be managed endoscopically with annual surveillance and
polypectomy, instead of performing prophylactic surgery in all.
9.17.3 Hyperplastic and Mixed Polyposis
These are rare and poorly understood conditions. It is clear that both are associated
with a substantially increased risk of colorectal cancer. A recent study [ 20 ] has
shown that in hyperplastic polyposis, fi rst-degree relatives without any evidence of
the condition are at a fi ve times increased risk of colorectal cancer compared with
the general population.
Colonoscopic surveillance of affected individuals and their fi rst-degree relatives
is recommended, at intervals dictated by polyp burden between 1 and 5 years.
9.17.4 Juvenile Polyposis
Juvenile polyposis is a dominantly inherited condition due to mutation in either the
SMAD 4 or BMPR1A gene. It is characterized by multiple juvenile-type hamar-
tomatous polyps throughout the colon, and some patients have additional pheno-
typic features.
There is an increased colorectal cancer risk, lifetime risk being somewhere
between 10% and 40%. In addition, there is a gastric cancer risk of around 25%.
Colonoscopic surveillance is recommended from the age of diagnosis, repeated
1–3 yearly depending on polyp burden. The majority of cases can be managed endo-
scopically by polypectomy, though sometimes colectomy is required.
9.17.5 Peutz Jeghers’s Syndrome
This is a rare hamartomatous polyposis syndrome that is dominantly inherited and
due to mutation in the STK11 gene. There is an increased risk of a range of cancers,
including an approximately 25% lifetime risk of gastrointestinal cancer [ 21 ] .
Total assessment of the gastrointestinal tract is recommended every 3 years con-
sisting of OGD, capsule endoscopy, and colonoscopy with removal of polyps.
120
S.K. Clark
This has the aim of preventing the complications associated with the polyps
themselves (anemia and intussusception) and also allowing cancer surveillance.
9.18 Summary
Successful population screening has the potential to prevent most cases of colorec-
tal cancer, but the challenge is to deliver effective screening, with high compliance
rates and safe, accurate, and affordable investigation.
It is also clear that a more intensive approach is needed in high-risk groups.
Much needs to be done both to identify individuals at increased risk and to refi ne
our understanding of these groups.
References
1. WHO. Cancer, fact sheet number 297. Geneva: World Health Organisation, 2009. http://www.
who.int/mediacentre/factsheets/fs297/en/index.html
. Accessed 22 Nov 2011
2. Cancer Research UK. By stage at diagnosis. London: Cancer Research UK, 2009.
http://info.
cancerresearchuk.org/cancerstats/types/bowel/survival/index.htm#stage
Accessed 22 Nov 2011.
3. Atkin W, Morson B, Cuzik J. Long-term risk of colorectal cancer after excision of rectosig-
moid adenomas. N Engl J Med. 1992;326:658–62.
4. Winawer SJ, Zauber AG, Ho MN, et al. Prevention of colorectal cancer by colonoscopic
polypectomy. The National Polyp Study Workgroup. N Engl J Med. 1993;329:1977–81.
5. Burch JA, Soares-Weiser K, St John DJB, et al. Diagnostic accuracy of faecal occult blood
tests used in screening for colorectal cancer: a systematic review. J Med Screen.
2007;14:132–7.
6. Baxter NN, Goldwasser MA, Paszat LF, et al. Association of colonoscopy and death from
colorectal cancer: a population based, case-controlled study. Ann Intern Med. 2009;150:1–8.
7. Brenner H, Hoffmeister M, Arndt V, et al. Protection from right- and left-sided colorectal
neoplasms after colonoscopy: population-based study. J Natl Cancer Inst. 2010;102:89–95.
Key Points
Colorectal cancer is a condition ideally suited to population screening •
A number of screening investigations exist, all with advantages and •
disadvantages
There is good evidence from a number of RCTs that FOBT screening •
reduces mortality from colorectal cancer
A recent large trial of fl exible sigmoidoscopy screening has shown reduc-•
tion in disease incidence as well as mortality
It appears that colonoscopy does not reduce the risk of developing proxi-•
mal colon cancer
There are a number of high-risk groups in whom surveillance for colorec-•
tal cancer should be undertaken
121
9 Colorectal Cancer Screening and Surveillance
8. Kronborg O, Fenger C, Olsen J, et al. Randomised study of screening for colorectal cancer
using faecal occult-blood test. Lancet. 1996;348:1467–71.
9. Kewenter J, Brevinge H, Engaras B, et al. Results of screening, rescreening and follow up in a
prospective randomized study for detection of colorectal cancer by fecal occult-blood testing:
results of 68,308 subjects. Scand J Gastroenterol. 1994;29:468–73.
10. Mandel JS, Bond JH, Church TR, et al. Reducing mortality by screening for fecal occult blood.
N Engl J Med. 1993;328:1365–71.
11. Hardcastle JD, Chamberlain JO, Robinson MH, et al. Randomised controlled trial of faecal-
occult-blood screening for colorectal cancer. Lancet. 1996;348:1472–7.
12. Hewitson P, Gasziou P, Irwig L, et al. Cochrane systematic review of colorectal cancer screen-
ing using the faecal occult blood test (haemoccult): an update. Am J Gastroenterol. 2008;103:
1541–9.
13. Atkin WS, Edwards R, Kralj-Hans I, et al. One-only fl exible sigmoidoscopy screening in pre-
vention of colorectal cancer: a multicentre randomised controlled trial. Lancet. 2010;9276:
1624–33.
14. Weller D, Coleman D, Robertson R, et al. The UK colorectal cancer screening pilot: results of
the second round of screening in England. Br J Cancer. 2007;97:1601–5.
15. Tappenden P, Chilcott J, Eggington S, et al. Option appraisal of population-based colorectal
cancer screening programmes in England. Gut. 2007;56:677–84.
16. Robb KA, Miles A, Wardle J. Demographic and psychosocial factors associated with per-
ceived risk for colorectal cancer. Cancer Epidemiol Biomarkers Prev. 2004;13:366–72.
17. Cairns SR, Scholefi eld JH, Steele RJ, et al. Guidelines for colorectal cancer screening and
surveillance in moderate and high risk groups (update from 2002). Gut. 2010;59:666–89.
18. Atkin W, Saunders B. Surveillance guidelines after removal of colorectal adenomatous polyps.
Gut. 2002;51(Suppl5):V6–9.
19. Vasen HFA, Mšslein G, Alonso A, et al. Guidelines for the clinical management of familial
adenomatous polyposis (FAP). Gut. 2008;57:704–13.
20. Boparai KS, Reitsma JB, Lemmens V, et al. Increased colorectal cancer risk in fi rst-degree
relatives of patients with hyperplastic polyposis syndrome. Gut. 2010;59:1222–5.
21. Beggs AD, Latchford AR, Vasen HF, et al. Peutz-Jeghers syndrome: a systematic review and
recommendations for management. Gut. 2010;59:975–86.
123
S.R. Brown et al. (eds.), Contemporary Coloproctology,
DOI 10.1007/978-0-85729-889-8_10, © Springer-Verlag London Limited 2012
10.1 Introduction
Imaging plays a pivotal role in the preoperative staging of malignant colorectal
cancer. Multidetector computed tomography (CT or MDCT) is the principal inves-
tigation in the staging of colon cancer while both CT and magnetic resonance imag-
ing (MRI), for local staging, have roles in the staging of rectal cancer. The
introduction of CT colonography (CTC), also known as virtual or CT colonoscopy,
has increased the sensitivity of CT in detecting small tumors and polyps. This clearly
has implications in the screening of both symptomatic and asymptomatic popula-
tions. Though MRI and CT scanning are the main tools for staging colorectal can-
cers, other imaging modalities may be occasionally used. Endoscopic ultrasound
(EUS) can be used to locally stage rectal tumors in certain cases, and EUS+FNA
(fi ne needle aspiration) may be employed to determine nodal involvement. Positron
emission tomography combined with CT (PET-CT) does not have a routine use in
the staging of colorectal cancer but may be used for problem solving and detecting
recurrent disease. In staging liver metastases, both MRI scanning (using liver-spe-
cifi c contrast agents) and contrast-enhanced ultrasound have roles. Double-contrast
barium enema (DCBE) is still in use but is being replaced by CTC due to its greater
accuracy (see below). Single contrast enema studies may still play a role in large
bowel obstruction but have been largely replaced by MDCT [ 1 ] .
R. Sethi , M.B.B.S., MRCS, FRCR (*) • S. H. Lee , M.B.B.S., FRCS (Ed.), FRCR
Department of Radiology ,
Manchester Royal Infi rmary ,
Manchester , UK
email: rishi.sethi@cmft.nhs.uk ; stephen.lee@cmft.nhs.uk
Chapter 10
Imaging in Colorectal Cancer
Rishi Sethi and Stephen H. Lee
124
R. Sethi and S.H. Lee
10.2 Bowel Cancer Screening and CT Colonoscopy
The National Bowel Cancer Screening Programme commenced in 2006 and is now
established nationwide. Currently, all men and women aged between 60 and 69 years
in England and Wales and between 55 and 69 years in Scotland are invited for
screening. Screening consists of testing for fecal occult blood (FOB). Those who
test positive are then offered a screening colonoscopy (see Chap. 8 ).
Though optical colonoscopy currently remains “the gold standard” when evaluat-
ing the colon, recent advances in CTC has meant that this technique has a sensitivity
approaching that of colonoscopy [ 2 ] . This is especially true for lesions > 6 mm in size
especially when interpreted by experienced radiologists, as demonstrated in the mul-
ticenter ACRIN trial (2007) (Table 10.1 ). Provisional results from the recent SIGGAR
trial, a large multicenter trial based in the UK of symptomatic patients, have shown
CTC is vastly superior to double-contrast barium enemas (DCBE) and shown equiv-
alent results to optical colonoscopy [ 3 ] . The trial has yet to be peer published, but
these results enhance the profi le of this technique. Sensitivity and specifi city of CTC
for polyps 5 mm or less is low, and lesions smaller than 6 mm are usually discounted,
though it is worth noting that 30–40% of these will be adenomas.
CTC involves patients undergoing standard bowel preparation with rectal insuf-
fl ation using between 4–6 litres of CO
2
(though air can be used) to distend the colon.
Once satisfactory colonic distension has been achieved as determined by the CT
scout view, the patients are scanned in both supine and prone positions. Patients must
therefore be relatively mobile, though those with limited mobility may be scanned in
a lateral decubitus position. Noncontrast studies are used for screening patients and
IV contrast reserved for symptomatic patients, which is useful for staging purposes.
Several reports describe the use of oral contrast as a stool-tagging agent which can
be subtracted out using widely available CT software packages [ 4 ] .
Complication rates are low with the main risks being perforation which is exceed-
ingly rare (rates quoted as low as 1 in 100,000 [ 5 ] ), risks of intravenous contrast
(contrast allergy and nephrotoxicity), and radiation exposure (estimated lifetime
risk of inducing cancer in a 50-year-old – 0.006%).
Interpretation requires appropriately well-trained staff with use of 2D and 3D
(Figs. 10.1 and 10.2 ) reconstructions, on a dedicated workstation. Virtual fl y-through
of the colon improves sensitivity especially for smaller lesions.
Extracolonic abnormalities are frequently encountered, in some studies quoted as
up to 50%, with up to 7–12% of patients likely to require further investigation [ 6 ] .
Table 10.1 Results from ACRIN trial 2007 for CTC in detecting polyps
>5 mm (%) >6 mm (%) >7 mm (%) >8 mm (%) >9 mm (%) >10 mm (%)
Sensitivity 65 78 84 87 90
90
Specifi city 89 88 87 87 86 86
PPV 45 40 35 31 25 23
NPV 95 98 99 99 99 99
125
10 Imaging in Colorectal Cancer
There are clearly benefi ts and disadvantages to CTC, and its role in screening is
yet to be fi rmly established. However, with improving sensitivity and specifi city,
some studies have advocated a role in triaging screening patients to those who will
require colonoscopy [ 5 ] .
10.3 Staging Colon Cancer
CT scanning is the principal investigation in the staging of colon cancer. It is used
to determine both local T staging and for the detection of nodal and metastatic dis-
ease. The TNM classifi cation can be applied to imaging to allow a provisional stag-
ing to be made.
Fig. 10.1 Endoluminal view ( top left ), virtual enema image ( right ), and multiplanar reformats
126
R. Sethi and S.H. Lee
10.4 T-Staging (Table 10.2 )
Fig. 10.2 CTC images
(prone and supine) 2D
demonstrating a 6 mm
midtransverse colon polyp
( yellow arrow )
Table 10.2 T-staging
Tx – Primary tumor cannot be assessed
T0 – Unable to assess primary tumor
Tis – Carcinoma in situ: intraepithelial/invasion of lamina propria (intramucosal)
T1 – Tumor invades submucosa
T2 – Tumor invades muscularis propria
T3 – Tumor invades pericolorectal tissues
T3a – Tumor invades through the muscularis propria into the subserosa or into
nonperitonealized pericolonic or perirectal tissues
T3b – T1 or T2 tumor with satellite deposits in pericolorectal tissues
T4a – Tumor penetrates the visceral peritoneum
T4b – Tumor directly invades or is adherent to other organs or structures
127
10 Imaging in Colorectal Cancer
10.4.1 T1 and T2
T1 tumors are limited to the submucosa, whereas T2 tumors extend into the muscu-
laris propria (but not beyond this). On CT, both stages appear similar with the salient
features being a well-defi ned lesion with intraluminal extension but preservation of
the outer smooth muscle layer and clear pericolonic fat. T1 and T2 tumors conform
to bowel wall contour without any distortion [ 7 ] (Fig. 10.3 ).
10.4.2 T3
This category refers to transmural penetration that falls short of involvement of the
overlying serosa or the deep adjacent organs or structures (e.g., bladder, uterus).
Early T3 tumors (those which have extended beyond muscularis propria by
1–2 mm) are diffi cult to detect as they are still beyond the resolution of CT, and
these may be downstaged on imaging as T2. More advanced T3 tumors are identi-
fi ed by stranding in the adjacent fat, the presence of satellite nodules, and distortion
of bowel wall contour (Fig. 10.4 ). Those with involvement of the subserosa of
greater than 5 mm depth are associated with a poorer prognosis [ 7 ] .
10.4.3 T4
Theses tumors may be subcategorized into T4a, tumors which have penetrated the
visceral peritoneum, and T4b, those tumors which have invaded an adjacent
Fig. 10.3 Postcontrast axial
CT image demonstrating a
histologically proven T2
proximal sigmoid tumor
( yellow arrows ) which is
confi ned to the bowel wall
without involvement of the
pericolonic fat
128
R. Sethi and S.H. Lee
structure/organ. Perforated tumors are inferred to have breached the peritoneum and
are therefore all regarded as T4a tumors [ 7 ] .
Additionally, T-staging extramural vascular invasion (EMVI) may also be detected
on CT and acts as an independent prognostic factor in colorectal cancer [ 7 ] .
10.5 Nodal Disease Staging
Accuracy of nodal staging is diffi cult using CT. CT is unable to detect micrometasta-
ses in small nodes and may wrongly call larger nodes, which later prove to be reac-
tive. It therefore has a poor sensitivity (range 66–83%) and specifi city (35–81%) [ 7 ] .
Features on CT which infer likely nodal involvement include size (>1 cm), clusters of
nodes (usually >3) and any enhancing node. Any node along the drainage pathway of
the tumor should be considered suspicious. Nodal staging is included in Table 10.3 .
The advent of recent trials using neoadjuvant therapy (e.g., FOxTROT trial) [ 8 ]
has highlighted the importance of accurate preoperative T-staging of tumors. Those
patients with advanced T3 or T4 tumors were eligible to be entered into the trial and
randomized into subgroups receiving neoadjuvant chemotherapy.
10.6 Dukes’ Staging
Though the TNM system has largely superseded the modifi ed Dukes’ classifi cation
in radiology, it still remains widely used clinically.
Fig. 10.4 A stenosing T3
distal sigmoid tumor ( yellow
arrow ) with extramural
extension of soft tissue ( white
arrow )
Table 10.3 Nodal staging
N0 – No nodes involved
N1 – 1–3 regional nodes involved
N2 – >4 nodes involved
129
10 Imaging in Colorectal Cancer
10.7 Staging Rectal Cancer
Total mesorectal excision, via either a low anterior resection or AP resection, is now
considered the operation of choice in the surgical management of rectal cancers.
Accurate preoperative staging infl uences not only the surgical management but also
the choice of neoadjuvant therapy for patients. Involvement of the circumferential
resection margin (CRM) is an independent risk factor for local recurrence and there-
fore survival. It is therefore vital to ascertain whether there is involvement of the
CRM (Fig. 10.5 ) as this is likely to impact on obtaining clear radial margins at
surgery.
The accuracy of MRI in T-staging rectal tumors only ranges from 67% to 83%.
This is mainly due to diffi culty differentiating between T1 and T2 tumors and also
differentiating the desmoplastic fi brotic response of some tumors leading to over-
staging of T2 tumors as T3. Rectal MRI, however, is highly accurate in determining
CRM involvement, with accuracy reported in excess of 90% (up to 100% in some
studies) [ 9 ] . The role of MRI therefore is to assess CRM and other organ involvement
(Fig. 10.6a, b ) and nodal disease.
TNM staging follows that of colon cancer. Patients are staged using a combina-
tion of MRI (for local staging) and CT thorax, abdomen, and pelvis (to stage meta-
static disease).
Those patients with T1/T2 disease and no other adverse features may be eligible
for surgery only as the mainstay of treatment (Fig. 10.7a, b ). Patients with early
disease (T1) may be amenable to transanal excision microsurgery (TEMS). However,
as mentioned, MRI has a poor accuracy when differentiating T1 from T2 lesions,
and EUS in these cases would be of benefi t.
Those with operable T2 disease and other adverse features (mesorectal nodes,
signs of extramural vascular invasion) may be suitable for short-course radio-
therapy so long as the CRM is not involved (margin >2 mm). Patients with T1/T2
low rectal/anorectal junction tumors should also be considered for neoadjuvant
Fig. 10.5 T2-weighted axial
MRI image demonstrating the
border of the mesorectal
fascia or circumferential
resection margin (CRM)
( yellow arrows )
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