Screening for Colorectal Cancer
Screening refers to tests performed on patients who have no symptoms. Screening is suitable for colorectal cancer for the following reasons:
- Most screening tests are easily performed with minimal complications.
- Polyps that are detected can be removed preventing the polyps from turning into cancer.
- When diagnosed in the early stages, the outcome for colorectal cancer is excellent.
There are many guidelines and criteria for screening. Generally, patients at risk of developing colorectal cancer should be screened. This includes:
- Age above 50 years with no other risk factors
- Family history of a close relative who has colorectal cancer
- Patients with family history of Familial Adenomatous Polyposis (FAP) or Hereditary Non-Polyposis Colorectal Cancer (HNPCC)
- Patients with inflammatory bowel disease
- Females with breast, ovarian or uterine cancer
Anyone who is concerned about developing colorectal cancer may be screened for it.
There are several tests that can be performed to screen for colorectal cancer. Each test has its advantages and disadvantages. You should discuss with your doctor regarding screening, and your doctor will be able to advise you which test is most suitable for you.
1. Faecal occult blood test
- This test detects minute amounts of blood in the faeces that are not detectable by the human eye. It is a sensitive screening tool. However, not all blood in faeces is due to cancer. Once this test is positive, the patient needs to undergo another test, such as colonoscopy, to determine the source of bleeding.
2. Barium enema
- This is a special X-ray in which liquid barium is instilled into the colon and X-rays are taken of the contrast in the colon. This is an accurate test and is fairly safe. The disadvantage of this test is that if any lesion is detected, the patient needs to undergo a colonoscopy for further evaluation.
- This is an endoscopic procedure where the left side of the colon is assessed. This procedure does not assess the entire large intestine. The risks associated with this procedure are fairly low.
- This is a procedure in which an endoscope is passed through the anus to assess the entire large intestine. This is a very accurate test for assessment of colorectal cancer.
- The advantages of performing a colonoscopy include:
1. biopsies can be taken if cancer is detected
2. polyps can be removed thereby preventing development of cancer
- The main complication of this procedure is the possibility of injury to the colon as a result of the colonoscopy.
5. CT Colography
- CT Colography, also known as Virtual Colonoscopy, is one of the ways to examine the colon. It is an alternative to colonoscopy. It is a radiological procedure and uses a CT scanner to capture images of the colon and rectum. Then powerful computers analyse these images and reproduce 2-dimensional and 3-dimensional images of the large intestine.