Colon cancer

Tests for the diagnosis of colorectal cancer

Tests for the diagnosis of colorectal cancer

In its early stages, the probability of cure greatly increases

Colorectal cancer screening often occurs after symptoms appear.

Most people with early-stage colon cancer have no symptoms of the disease, and they only begin to appear when the disease is more advanced.

If colorectal cancer is detected, diagnosed and treated early, the chances of a cure are increased.

The detection techniques and diagnostic procedures most used in colorectal cancer are:

Stool blood test

This test detects the presence of blood in a stool sample from the patient.

This test is not 100% reliable since not all types of colorectal cancer cause bleeding, therefore false negative results may appear, that is, the presence of blood in the stool is not detected despite the fact that the patient could have Cancer.

Also, if blood is detected, this can be caused by other diseases or conditions such as hemorrhoids.

DNA markers

This test looks for some DNA markers present in colon cancer cells or in precancerous polyps, and that are shed in the stool.

This test is much more accurate for detecting colon cancer, but it is not capable of detecting all DNA mutations associated with the presence of tumors.

Flexible sigmoidoscopy

The sigmoidoscope is a thin, lighted, flexible tube with which the doctor examines the patient's rectum and the sigmoid colon (the part of the colon before the rectum).

Although the test is not painful, it can be a bit uncomfortable.

Sigmoidoscopy can only detect polyps or precancerous lesions present in the final part of the colon and in the rectum.

Barium enema and X-ray

Barium is a contrast liquid that is put into the intestine of the patient in the form of an enema, it covers the lining of the intestine and creates a clear image of the rectum and the end of the colon. This procedure is sometimes done in conjunction with a sigmoidoscopy to detect small polyps with the barium enema x-ray.


The colonoscope is a flexible tube much longer than a sigmoidoscope, which is attached to a video camera and a monitor. With this procedure, the entire colon and rectum can be visualized.

Polyps found during a colonoscopy can be removed during the test. It is a painless procedure, although sometimes it is necessary to administer a mild sedative to patients so that they can undergo the test with more confidence.

Virtual colonoscopy

Images of the colon are taken through a computed tomography (CT) scan.

Although it is a minimally invasive technique and well tolerated by patients, it is unreliable since the results obtained with it are not decisive.

If something abnormal is detected, the patient will have to undergo a conventional colonoscopy.


This technique is used primarily to detect the presence of metastases.

Magnetic resonance

This procedure allows three-dimensional imaging of the intestine, which can be very useful for diagnosis.

Keep reading:

Video: Colorectal cancer diagnostic testing and screening options (July 2021).