What tests are needed for colorectal cancer screening

We know that colonoscopy screening can detect colorectal cancer at an early stage, thereby increasing life expectancy. However, the question is how to develop an effective and convenient screening program. From a medical perspective, successful screening should be screening and accurately diagnose asymptomatic diseases at a treatable stage of the disease.

1. Occult blood test

It is the most common method for diagnosing colorectal cancer. According to clinical observations, colorectal cancer can usually cause patients to show varying degrees of bleeding. Therefore, a simple and easy fecal occult blood test can be used to monitor the disease. The early fecal occult blood test was a chemical colorimetric method, and commonly used reagents were benzidine or guaiac. In recent years, it has gradually been replaced by more specific immune occult blood reagents, but because the fecal occult blood test cannot distinguish between cancerous and non-cancerous bleeding, it is currently mostly used as a preliminary screening method for large-scale population surveys.

2. Rectal mucus T antigen test

In clinical practice, this test is also called the galactose oxidase test. Generally, this test is a simple method to detect specific markers of precancerous lesions. Just smear the liquid on the rectal finger sleeve on a special paper film or glass slide, and then use the galactose oxidase reaction and Schiff's reagent to develop the color. It can be determined whether the patient's intestinal mucosa expresses T antigen. Clinical and survey verification show that this method has high sensitivity and specificity for the detection of colorectal cancer.

3. Detection of serum CEA

Clinical investigations and statistics over the years have found that serum CEA levels are often elevated in most patients, but the test is not specific, and serum levels can also be elevated in some non-digestive tract tumors and benign lesions. In addition, CEA has poor sensitivity to early colon cancer and adenomatous polyps. Therefore, its use in early colorectal cancer detection is not effective.