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.

Colonoscopy and FOBT (Fecal occult blood testing) are used for screening.

1 . Involves using an endoscope inserted via the anus to visualize the entire colon and rectum directly. It is used for screening in patients considered high risk for colorectal cancer.

Advantages

1. High sensitivity for cancer and all classes of precancerous lesions
2. Diagnosis and treatment can be done in a single session
3. 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.

Disadvantages

Include the need for thorough bowel cleansing and procedure-related complications like perforation and sedation risks. However, these are rare when the procedure is done by skilled personnel.

2. Fecal occult blood testing(FOBT) – Involves checking of blood in stool that may not be visible. Types available are guaic Fecal Occult Blood (gFOBT) testing and Fecal

immunochemical Test (FIT). In Kenya, gFOBT is the most widely available test.

Advantages of FOBT include its noninvasive nature and low cost. 

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