Double-contrast barium enema can detect most of the clinically important lesions in the colon but, as

with colonoscopy, its effectiveness as a screening test for CRC is based only on indirect evidence.

Similar to colonoscopy, it requires dietary modification and mechanical bowel preparation, and is

associated with patient discomfort. In addition, a positive test mandates a colonoscopy. While doublecontrast barium enema every 5 years should provide the same degree of protection as the other

screening strategies, it is rarely used as a primary screening method today. Its clinical role as a

screening tool at this time is primarily for visualization of the colon in patients who cannot undergo a

complete colonoscopy.

Computed tomography colonography (CTC), also referred to as virtual colonoscopy, involves thinsection, multidetector, helical CT, and three-dimensional viewing for interpretation.88 CTC identifies

90% of cancers or adenomas measuring more than 10 mm in diameter in asymptomatic individuals 50

years of age or older.89 It is more sensitive than other screening methods, but can miss flat lesions and

polyps smaller than 10 mm in diameter. CTC obviates some of the drawbacks of colonoscopy, such as

the need for sedation and recovery time, but also has downstream consequences: it delivers a dose of

radiation that may become substantial with repeated examinations, and detects incidental extra-colonic

findings that may trigger expensive, and sometimes unnecessary diagnostic investigations. Furthermore,

it requires standard bowel preparation and gaseous distension of the colon. New methods of tagging and

subtracting residual stool may obviate the routine need for mechanical bowel preparation. Finally,

patients with lesions found on CTC still require full visualization of the colon by colonoscopy. CTC is

now considered an acceptable screening alternative for average-risk individuals, starting at 50 years of

age; the interval between such examinations remains uncertain, although a 5-year interval has been

suggested, based on computer simulation models.90

Risk Categories

Patients with symptoms of CRC should undergo the appropriate diagnostic studies; they are not

candidates for screening. Screening recommendations for the general population are based on individual

risk assessment. Based on the past medical history and family history of CRC or polyps, individuals are

assigned to one of three risk categories, with different screening recommendations (Table 68-7).91

Average Risk

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People at average risk for the development of CRC (asymptomatic men and women without risk factors,

over 50 years of age in the United States and 60 in the United Kingdom) could undergo yearly FOBT,

combined with flexible sigmoidoscopy every 5 years. People with a positive FOBT or a polyp identified

by flexible sigmoidoscopy should undergo entire colon and rectum examination by colonoscopy. Doublecontrast barium enema every 5 years, or colonoscopy every 10 years, is an accepted screening

alternative in the average-risk population. CTC every 5 years is also an option. Digital rectal

examination (DRE) should be performed at the time of sigmoidoscopy or colonoscopy in all individuals.

Increased Risk

Family History. Individuals with a first-degree relative (parent, sibling, or child) with CRC or

adenomatous polyps diagnosed before 60 years of age should start screening with colonoscopy at 40

years of age or 10 years younger than the earliest diagnosis in their family, whichever comes first. The

test should be repeated every 5 years. Individuals with one first-degree relative with CRC or

adenomatous polyp diagnosed at 60 years of age or older, or with two or more second-degree relatives

(grandparent, grandchild, aunt, uncle, niece, nephew, half-sibling) with CRC or adenomatous polyps at

any age, should undergo screening as average-risk individuals – but starting at 40 years of age. Patients

with one second-degree relative or one or more third-degree relatives (first cousin) affected are

considered to be at average risk.

History of Polyps at Previous Colonoscopy. Patients undergoing endoscopic excision of a small (<1

cm) adenomatous polyp should have the entire colon examined at the time of the polypectomy.

Colonoscopy should be repeated 5 years later. If the test is negative, they should then follow the

screening recommendations for average risk.92

Patients with more than three adenomas, adenomas with villous features or high-grade dysplasia, or a

large adenomatous polyp (>1 cm) who have the entire colon examined at the time of polypectomy,

should undergo complete colonoscopy 3 years later – and, if normal, every 5 years thereafter.

A complete colonic examination should be carried out before surgery in any patient undergoing a

planned curative resection for CRC. The colonoscopy should be repeated at 1 year to exclude

metachronous lesions. If the examination at 1 year is normal, it should be repeated after 3 years, and

every 5 years thereafter if the previous one was normal.

Patients with Colorectal Cancer. Patients with colon and rectal cancer should undergo high-quality

perioperative clearing of polyps with colonoscopy 3 to 6 months after resection, if not performed before

surgery. Surveillance after curative resection is described in detail in Surveillance after Curative

Resection for Colon and Rectal Cancer section.

High Risk

This category includes individuals from families diagnosed with hereditary forms of CRC.

Familial Adenomatous Polyposis. Once the diagnosis of FAP is established, the patient should

undergo colectomy, or a yearly colonoscopy until colectomy. Upper gastrointestinal endoscopy should

be performed every 1 to 2 years. Siblings and children of a patient with FAP should start surveillance by

flexible sigmoidoscopy at puberty.

MYH-Associated Polyposis. Depending on the individual, age of presentation, and number and size of

polyps, the patient may be advised to undergo a prophylactic colectomy or yearly colonoscopy

beginning at 25 years of age. Upper gastrointestinal surveillance should be performed following the

guidelines for patients with FAP.

Lynch Syndrome. Individuals from families fitting the Amsterdam criteria for HNPCC should have a

colonoscopy at 21 years of age, then every 2 years until 40 years of age, and yearly thereafter. Genetic

counseling and testing should be considered.

At-risk members of families with hereditary cancer syndromes should be informed about the benefits

and limitations of genetic counseling and genetic testing.

Consequences of Screening

The full spectrum of clinical consequences of screening, other than the prevention of deaths from CRC,

is difficult to predict because every screening strategy initiates a cascade of events, each one with

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uncertain probability. The rate of false-positive tests, the number of colonoscopies performed, the

complications of the screening and diagnostic tests, and the number of patients who may require

surveillance as a consequence of screening, are complex factors that arise at different times over several

decades. However, cost-effectiveness analysis in the United States has demonstrated that screening for

CRC in average-risk patients, according to the strategies outlined above, compares favorably with other

healthcare interventions such as mammography or treatment of mild hypertension.93,94 It is important

to understand that screening does not completely eliminate the risk of CRC. Up to 9% of CRCs are

diagnosed within 6 to 36 months after a screening colonoscopy.95,96 These interval cancers tend to be

preferentially located in the proximal colon. This may be related to failure to reach the proximal colon,

residual stool obscuring the view in the proximal colon, or different characteristics of the proximal

lesions that makes them more difficult to detect or remove.

Implementation of Guidelines

The general population has limited awareness of the risks of CRC or its symptoms; as a result the

number of individuals participating in screening programs has been low. The dissemination of

information to patients is an essential part of the screening program. Primary care physicians have a

responsibility to inform their patients about their risk of CRC, the benefits of screening and different

screening strategies, and to set up a system for implementing these guidelines.94,97,98 Through such

efforts, the proportion of adults 50 to 75 years of age having colonoscopy has increased steadily in the

last decade: from 19.1% in 2000 to 55% in 2010.3

DIAGNOSIS

While the proportion of CRCs diagnosed through screening is increasing, most are still diagnosed after

patients become symptomatic. CRC can cause a myriad of symptoms, many of which are nonspecific and

highly prevalent among healthy individuals. Therefore, the diagnosis of colorectal carcinoma often

requires a high index of suspicion.

Symptoms and Signs

The most common symptoms in patients with CRC are abdominal pain, change in bowel habits, rectal

bleeding, anemia, anorexia, and weight loss. The clinical manifestations of CRC differ depending on the

location and stage of the tumor.

Abdominal pain is nonspecific; it may be localized to any quadrant of the abdomen, or may be diffuse.

When the pain is persistent and colicky, it is more likely to represent obstructive symptoms resulting

from a left-sided lesion. More localized tenderness with signs of localized peritonitis indicates local

invasion of the adjacent peritoneum or perforation. It can be difficult to distinguish the pain associated

with diverticular disease from that due to a carcinoma in the sigmoid or descending colon. Patients with

diverticular disease may also have an underlying carcinoma. Abdominal pain may occasionally be

related to extensive metastatic disease in the liver or retroperitoneal lymph nodes. Rectal cancer can

also cause perineal discomfort and is often associated with tenesmus, the sensation of incomplete

defecation. A locally advanced rectal cancer can also cause sacral or sciatic pain.

An unexplained change in bowel habits lasting more than 2 weeks requires investigation for CRC.

Constipation associated with colicky abdominal pain is a common manifestation of partially obstructing

tumors. Abdominal pain, constipation, and abdominal distension suggest a complete colonic obstruction,

which is more common in tumors located in the sigmoid colon and rectum. Some patients with sigmoid

or rectal cancer may also complain of diarrhea, which may sometimes be bloody.

Bleeding from tumors in the sigmoid colon and rectum is often wrongly attributed to hemorrhoids or

other benign anal conditions. However, blood from hemorrhoids is usually bright red and is

accompanied by anal discomfort; the bleeding is intermittent and splashes the toilet pan. Anal fissure is

also a common cause of rectal bleeding; the blood is often bright, occurring after defecation, and is

typically associated with sharp anal pain triggered by defecation. Painless defecation with rectal blood

that is darker in color and mixed in with stool is more likely to be secondary to an underlying

carcinoma. Rectal bleeding, particularly when associated with tenesmus, requires a thorough diagnostic

investigation to exclude an underlying rectal tumor.

The development of nonspecific anemia of unknown origin is a common manifestation in patients

with a carcinoma in the proximal colon. Patients with unexplained microcytic anemia should be

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examined initially with colonoscopy. Anorexia and weight loss frequently accompany CRC, and are

often associated with advanced disease. The differential diagnosis in these patients is a gastric

carcinoma, but when investigations are negative it is important to exclude a large-bowel malignancy. As

the bowel lumen is larger and the stools overall looser in the proximal colon, obstructive symptoms are

uncommon; therefore, patients with tumors proximal to the splenic flexure often present with advanced

disease.

It should be remembered that the presence of colon cancer can also be identified incidentally during

investigations for other pathologies such as gallstones, gynecologic, or urinary conditions. A complete

family history, with emphasis on past history of CRC or polyps, is essential to diagnose some hereditary

cancer syndromes. A family history of endometrial, gastric, urologic, or other HNPCC-associated cancers

is also important because it may help in diagnosing Lynch II syndrome.

The evaluation of patients suspected of CRC requires a complete physical examination. Features that

should arouse suspicion of malignancy include pallor, palpable abdominal mass, and a palpable mass on

DRE. Hepatomegaly indicates advanced disease with extensive liver metastases, and consequently a

very poor prognosis. A hard mass in the pouch of Douglas felt on DRE may indicate peritoneal

carcinomatosis. Other signs of an underlying CRC include pneumaturia, ischiorectal or perineal

abscesses, or even deep venous thrombosis.

The differential diagnosis of CRC includes diverticulitis, irritable bowel syndrome, inflammatory

bowel disease, ischemic colitis, and benign anorectal conditions such as hemorrhoids or rectal mucosal

prolapse.

Diagnostic Evaluation

Patients with symptoms suggesting CRC should have a colonoscopy to evaluate the entire colon (Fig.

68-7). The examination should be complete, as up to 4% of patients with CRC have synchronous cancers

and many more have colorectal polyps.99,100 Up to one-third of these synchronous cancers are in

locations requiring a different surgical resection, further emphasizing the importance of complete

colonoscopy. As many patients undergo minimally invasive surgery today, the endoscopist should mark

the vicinity of the tumor with India ink to help locate the lesion intraoperatively. CT colonography and

DCBE are less effective in investigating patients with symptoms suggestive of CRC, but they are useful

in patients with partially obstructive tumors, in whom colonoscopy cannot be completed. In patients

with obstructive lesions, the proximal colon can be examined either by preoperative imaging studies

such as PET-CT, or intraoperatively by direct palpation of the colon. In any case, patients with a

complete colonoscopy before surgery should have a surveillance colonoscopy 6 months after surgery.

Assessment of the extent of disease at the time of diagnosis is important because clinical stage,

particularly in rectal cancer, dictates treatment decisions. A CT scan of the chest, abdomen, and pelvis

with intravenous and oral contrast is important in order to locate the tumor, detect mesenteric nodes,

and exclude liver metastasis and gross peritoneal carcinomatosis (Fig. 68-7). In addition, preoperative

imaging helps the surgeon plan the resection. In patients with iodine allergy, and in patients with

undetermined lesions on CT, a PET-CT or and abdominal or pelvic MRI may provide additional

information.

Laboratory evaluation includes complete blood cell count, coagulation parameters, and chemistry

panel. Preoperative CEA should be measured because it provides prognostic information, and can be

useful during patient surveillance.

TREATMENT

Surgery is the primary treatment for CRC, but for many patients surgery is not the initial form of

treatment and some do not require surgery at all. Treatment is different for colon than for rectal cancer,

and depends also on the clinical stage of the tumor. Treatment decisions must also take into account the

patient’s performance status, comorbidities, hereditary CRC predisposition, as well as desires and

expectations.

Preoperative Preparation

All patients undergoing surgery for colon and rectal cancer require similar preoperative preparation

aimed at optimizing the technical success of the procedure and avoiding perioperative complications.

Surgical site infection (SSI) is the most common complication after colon and rectal cancer resection,

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