• Age to begin screening is 45 years for average-risk persons.

• OBT is the recommended screening test in average-risk persons

• Colonoscopy is recommended for high-risk persons

• More frequent screening in high-risk persons – on average, every 5 years.

• Genetic testing for familial CRC


Colorectal cancer is a leading cause of cancer morbidity and mortality worldwide, with

Colorectal cancer is a leading cause of cancer morbidity and mortality worldwide, with

1,849,518 new cases and 880,792 deaths in 2018. In Kenya it is among the top cancers affecting both men and women, with the number of new cases estimated at 2,316 and deaths at 1,466 (GLOBOCAN, 2018). It is preventable since most colorectal cancers de- velop from precancerous polyps which when detected early can be removed. It can also be cured if diagnosed early.

Patients normally present with a change in bowel habits (diarrhea or constipation), per rectal bleeding, persistent abdominal discomfort (cramps, bloating/flatulence, abdom- inal pain), tenesmus (feeling of incomplete bowel emptying), weakness or fatigue or unexplained weight loss, iron-deficiency anemia and intestinal obstruction. However, many people with colon cancer experience no symptoms in the early stages of the dis- ease. When symptoms appear, they will likely vary, depending on the size of the cancer and location in the large intestine. The symptoms are relatively non-specific and may mimic other conditions such as gastro-intestinal infections and other inflammatory con- ditions. Therefore, a high index of suspicion is required.

Majority of colorectal cancers arise from polyps. The two classes of precancerous lesions that predispose to colorectal cancer are conventional adenomas and serrated polyps



Non-modifiable risk factors

• Older age – greater than 45 years old

• Inflammatory bowel disease such as Crohn’s disease or ulcerative colitis.

• A family history of colorectal cancer or colorectal polyps.

• Presence of genetic syndromes like familial adenomatous polyposis (FAP) or

hereditary non-polyposis colorectal cancer (Lynch syndrome)

Modifiable risk factors

• Intake of red and processed meats

• Physical inactivity

• Low fruit and vegetable intake

• A low-fiber and high-fat diet

• Obesity

• Alcohol intake

• Tobacco use


Colorectal cancer is associated with high morbidity and mortality rates in Kenya. Ma- jority of colorectal cancer cases are locally invasive or distantly metastatic at diagnosis. Screening provides an opportunity for detection and removal of pre-cancerous lesions which prevent or delay the occurrence of colorectal cancer. In addition, detection of early stage disease allows early therapeutic intervention/treatment with good clinical outcomes.

The aim of colorectal cancer screening is the detection of precancerous lesions (adeno- mas and serrated polyps) and early cancer lesions.


There are various approaches that may be used for screening colorectal cancer.

This guideline recommends using the risk-stratified approach. This where the patient’s risk for advanced adenoma is assessed and the patient classified as per risk status, ei- ther as high risk or low risk. We also recommend starting with FOBT and then guided screening for low risk clients. For high risk clients (refer to Table 1 for risk stratification), colonoscopy is the recommended modality for screening.

Other approaches to screening

In settings of opportunistic screening, various approaches may be used to offer screen- ing to patients as described below:

i. Multiple screening options

This is whereby the client is informed about all the available screening modalities (FOBT and colonoscopy) and they choose their preferred method. It is usually helpful in well-re- sourced settings.

ii. Sequential approach

This involves a step-wise approach where the most effective screening modality is first recommended to the patient then a less preferred option is offered subsequently if the patient declines the initial method. This guideline recommends that for opportunistic screening, colonoscopy should be offered first and FOBT next. However, for the pro- grammatic screening, FOBT should be offered first then colonoscopy.

Guideline recommendations

• Risk stratified approach is most recommended

• In low risk patients, begin with FOBT then guided screening.

• For high risk patients, risk stratification should be done and coloscopy


CRC screening tests are based on performance features, costs, and practical consider- ations. Colonoscopy and FOBT are recommended as the cornerstones of screening re- gardless of the screening approach taken.


Colonoscopy involves using an endoscope inserted via the anus to visualize the entire colon and rectum directly.

The advantages of colonoscopy include:

• High sensitivity for cancer and all classes of precancerous lesions

• Diagnosis and treatment can be done in a single session

• It allows for long intervals between examinations (10 years) in subjects

with normal findings. One or 2 negative examinations may signal lifetime protection against CRC.

It is ideal for patients who value the highest level of sensitivity in detection of precancer- ous lesions and are willing to undergo invasive screening.

Disadvantages of colonoscopy include the need for thorough bowel cleansing and pro- cedure-related complications like perforation and sedation risks. However, these are rare when the procedure is done by skilled personnel.

Fecal occult blood testing (FOBT)

Fecal occult blood testing can be either guaic fecal occult blood (gFOBT) testing or Fecal immunochemical Test (FIT). In Kenya, gFOBT is the most widely available test. Advantages of FOBT include its noninvasive nature and low cost. FIT is more sensitive than gFOBT.

FOBT is recommended annually and is commonly the test of choice in programmatic screening. It is also one of the tests that can be used in sequential or multiple-options approach.

Disadvantages of FOBT include the need for repeated testing and poor sensitivity for some precursor lesions.

Flexible sigmoidoscopy

This can be an option to colonoscopy in settings lacking adequate infrastructure to sup- port a full colonoscopy.

Advantages of flexible sigmoidoscopy include:

• Lower cost and risk compared with colonoscopy

• Limited bowel preparation required

• No need for sedation

Disadvantages of flexible sigmoidoscopy include:

• Lower benefit in protection against right-sided colon cancer compared to


• Relative patient discomfort due to lack of sedation

Flexible sigmoidoscopy, when used, is often recommended at 5-year intervals. Patients with a positive FOBT and negative flexible sigmoidoscopy should have a full colonosco- py done since it is possible that they may be having a right-sided adenoma or cancer.

Double Contrast Barium Enema (DCBE)

The DCBE is a relatively low risk procedure, less invasive and more affordable than colo- noscopy. It can be easily done in any facility with an X-ray machine.

However, a negative result does not rule out abnormalities or colorectal cancer. There- fore, the patient still requires a follow-up colonoscopy.

The disadvantages of the procedure include allergic reactions and procedure-related risks.

Virtual (CT) colonoscopy

This is a reconstruction of the colon from CT scan images. It may be used as an alterna- tive to DCBE and in settings where contraindications to colonoscopy may exist. Advantages:

• Minimally invasive screening procedure therefore lower complication


• Takes less time

• Less vigorous bowel preparation due to tagging of residual stool and


• Can visualize colon beyond an obstruction or narrowing

• Detects both colonic and extra-colonic pathology


• Small risk of perforation

• High cost as compared to DCBE and FOBT

• Any positive findings will require conventional colonoscopy for


• Exposure to low-level ionizing radiation

• Any residual/untagged faecal matter can give rise to wrong


• There is currently no evidence to test and demonstrate survival benefit


Screening is conducted in asymptomatic patients without prior colonoscopy unlike surveillance where colonoscopy is performed in patients with previous precancerous or dysplastic lesions, inflammatory bowel disease or after another positive screening test.

Persons at average risk (asymptomatic healthy individuals without family history) should begin screening for colorectal cancer at age 45 years in Kenya (Rex et al, 2009). The recommended screening modality is annual FOBT followed by colonoscopy. If the initial colonoscopy findings are normal, repeat the colonoscopy after 10 years. If the screening is done using FOBT, screen the patient annually. Other screening options include a flexible sigmoidoscopy, Virtual colonoscopy or a double-contrast barium enema every 5 years. If any of the alternative tests are positive, the patient should have a colonoscopy done.

Persons with a family history of CRC or a documented advanced adenoma in a first-de- gree relative age <50 years or 2 first-degree relatives with these findings at any age are recommended to undergo screening by colonoscopy every 5 years, beginning at age 40 years or 10 years before the age at diagnosis of the youngest affected relative, whichever comes earlier.

Persons with a single first-degree relative diagnosed at �50 years with CRC or an ad- vanced adenoma can have 10-yearly colonoscopy from 40 years of age, or 10 years earlier than the youngest relative diagnosed with CRC, whichever comes earlier.

Summary of Risk Stratification

1. Average risk • Age A years

• Asymptomatic

• No family history of


• Screening should be initiated from

45 years of age

• The patient should be offered FOBT

using FIT and then colonoscopy.

• Colonoscopy should be offered every 10 years if the initial one is normal.

• FOBT using FIT can be offered annually if the initial one is negative Positive tests should be followed by colonoscopy.

• Patients can be offered -yearly sigmoidoscopy if the colonoscopy is not available

2. Increased risk • CRC in one first- degree relative A 0 years or

• an advanced adenoma in one first-degree relative

diagnosed A 0 years

• 10-yearly colonoscopy from 40 years of age, or 10 years earlier than the youngest relative diagnosed with CRC, whichever comes earlier
• Persons with multiple first-degree relatives or other relatives with CRC diagnosed at >50 years • 5-yearly colonoscopy from 50 years of age, or 10 years earlier than the youngest relative diagnosed with CRC whichever comes earlier
3. High risk • Hereditary or genetic • Genetic counselling and testing predisposition, • Colonoscopy should be done from

e.g. FAP, polyposis

syndrome, age of 10 years with FAP, 18 years

for HNPCC, 10 years earlier than the

• Non-hereditary polyposis affected relative

• Inflammatory bowel



Discontinuation of screening should be considered when persons up to date with screening, who have prior negative screening (particularly colonoscopy), reach age 75 or have less than 10 years life expectancy.

Persons without prior screening before the age of 75 years should be considered for screening up to age 85, depending on comorbidities.


FOBT can be performed in an appropriately equipped laboratory. A level III facility and above should be able to do this test. If positive, the patient should have a colonoscopy. Colonoscopy: A trained endoscopist should perform the colonoscopy.

Genetic testing: This should also be done in an appropriately equipped laboratory.


Colonoscopy and sigmoidoscopy should be offered from a Level 5 facility or higher. It should be well equipped with facilities for management of procedure complications such as complications of sedation or gut perforation. The recommendation for colonos- copy at Level 5 or higher is informed by staffing and safety considerations as well as the need to create high volume centers.

FIT and DCBE should be done in facilities with the requisite expertise (laboratory and radiology respectively). This guideline recommends for Level 3 facilities and higher to be able to conduct FOBT.


Symptoms of colorectal cancer


I No



I � I I


Diagnostic studies

·1 I




1• •1 Increased I

I Ag I


.. I •

I History I


I <45yr


I I �45yr I

I Personal history


I Family history I

Do not screen



Adenomatous polyps

Colo rectal Inflammatory

I cancer bowel

,, ,,



” Genetic • Colorectal cancer syndromes in 1 or 2 pt_

• Annual FOBT

– • Colonoscopy every lOyr

(FAP, HNPCC) degree relatives

• Adenoma polyps

in pt-degree

• Flexible sigmoidoscopy relative <60y every 5 yr

• FOBT and Flexible sigmoidoscopy

• DCBE every 5-lOyr ,. ,,

Screening, Same screening


Positive genetic options as for counselling average risk but genetic testing starting at 40 yr



” ‘

Evaluation of entire colon • Colonoscopy Key: DCBE, double-cont ast


• Colonoscopy • Alternative: Consider barium enema; FAP, fam ilia I

• Alternative for positive DCBE, surveillance adenomatous polyposi s;

FOBT: DCBE, preferably with colonoscopy FOBT, Fecal occult blood test;

preferably with flexible flexible HNPCC, hereditary sigmoidoscopy sigmoidoscopy nonpolyposis colorectal


Adapted from Center for Colon and Rectal Surgery 2009 (original source: Winswer SJ, Fletcher RH, Miler L,, Colorectal cancer screening; clinical guidelines and rationale, Gastroenterology)


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