How to diagnose mid-term colorectal cancer

Because some symptoms of colorectal cancer are confused with other related intestinal symptoms, misdiagnosis often occurs, which will delay the treatment and cause great harm to the patient. There are many methods for diagnosing colorectal cancer, such as stool testing and serological testing. Let's explain the diagnosis of colorectal cancer.

1. Fecal occult blood test: There are immunological and chemical methods. The sensitivity and specificity of the immunological method are higher than those of the chemical method. This method is often used in the initial screening of colorectal cancer, and those with positive occult blood will undergo further endoscopic examination. Since colorectal cancer often presents with varying degrees of bleeding due to mucosal erosion and ulceration, a simple and easy fecal occult blood test can be used to monitor colorectal cancer. 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 In recent years, it has gradually been replaced by more specific immune occult blood reagents, but since the fecal occult blood test cannot distinguish between cancerous and non-cancerous bleeding, it is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 colorectal cancer screening.

2. Rectal mucus T antigen test: also known as galactose oxidase test, it is a simple method to detect specific markers of colorectal cancer and precancerous lesions. Just smear the liquid on the rectal finger sleeve on a special paper film or glass slide, and then use galactose oxidase reaction and Schiff's reagent to develop the color, then it can be determined whether the patient's intestinal mucosa expresses T antigen. Clinical and general surveys have verified that this method has high sensitivity and specificity for the detection of colorectal cancer. Using it for general surveys and immune occult blood tests to screen for colorectal cancer has a complementary effect, but there are also certain false positive and false negative rates.

3. Serum CEA detection: Serum CEA levels are often elevated in most colorectal cancer patients, but the specificity of this test is not strong. 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, so its use in early colorectal cancer detection is not effective.