Blood test for colorectal cancer is negative

Colorectal cancer is one of the most common cancers. It is very harmful to people's health. Colorectal cancer patients suffer endless torture from the disease. Their health is getting worse and worse, their resistance and immunity are getting lower and lower, and they are very likely to suffer from other types of diseases. Let's take a look at what examinations are performed on colorectal cancer patients?

1. Laboratory examination

In addition to routine blood tests to understand whether the patient has anemia, other laboratory tests can be performed according to the needs of diagnosis and differential diagnosis. Among them, fecal occult blood test and detection of colorectal cancer biological markers are of positive significance for the early diagnosis of colorectal cancer.

1. Fecal occult blood test

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. Early fecal occult blood tests were chemical colorimetric methods, and commonly used reagents were benzidine or guaiac. In recent years, they have gradually been replaced by more specific immune occult blood reagents. However, since fecal occult blood tests cannot distinguish between cancerous and non-cancerous bleeding, they are currently mostly used as a preliminary screening method for large-scale population colorectal cancer surveys. However, a few early cancers may also show false negative results and lead to missed diagnosis.

2. Rectal mucus T antigen test

Also known as the galactose oxidase test, it is a simple method for detecting specific markers of colorectal cancer and precancerous lesions. Just smear the liquid on the rectal finger cot on a special paper film or glass slide, and then determine whether the patient's intestinal mucosa expresses T antigen through galactose oxidase reaction and Schiff's reagent color development. Clinical and survey verification shows that this method has high sensitivity and specificity for the detection of colorectal cancer. Its use in surveys has a complementary effect with the immune occult blood test for colorectal cancer screening, but there is also a certain false positive and false negative rate.

2. Endoscopic examination

It has been widely promoted and applied in clinical practice. Routine X-ray examinations are often performed for experienced endoscopists. Full colonoscopy is especially recommended for clinical patients with highly suspected colorectal cancer to avoid missed diagnosis. Because fiber colonoscopy is safe and reliable, it can not only examine the size, shape, location, and mobility of the tumor, but also perform polyp or early micro-cancer resection, and can take tissue biopsy from suspicious lesions through a directional microscope. Therefore, it is currently the most effective means of diagnosing colorectal cancer. In colorectal cancer surveys, it is often used as the gold standard for evaluating the effectiveness of various initial screening tests.

3. X-ray examination

It can detect lesions that cannot be seen by a proctoscopy or sigmoidoscope. It is especially important for patients in whom fiber colonoscopy is difficult to reach the ileocecal region. It is also an effective means of diagnosing colorectal cancer. Generally, a barium meal enema examination is performed. The main signs are local deformation of the mucosa, abnormal peristalsis, intestinal stenosis, filling defects, etc. It is often difficult to show smaller early cancers, especially those with a diameter of less than 2 cm. The use of air-barium double development is helpful for the detection of early cancers.

IV. Others

For example, B-ultrasound examination, CT tomography, magnetic resonance imaging, angiography, and lymph node 99mTc isotope scanning are used in the clinical diagnosis of colorectal cancer, with mixed results.

Through the introduction of the above content, we gradually learned about the examination items that colorectal cancer patients undergo. We hope that these contents can be helpful to the majority of patients. Colorectal cancer patients must go to the hospital in time to receive regular examinations and actively cooperate with treatment so that their bodies can overcome the disease faster and regain a healthy body.