The immunoassay of screening du colorectal cancer replaces, since May 2015 in France, the Hemoccult II test, which made it possible to detect the presence of blood in the stools and therefore the possible presence of a colorectal tumor or a precancerous lesion.

This test is more efficient: it would detect 2 to 2,5 times more cancers and 3 to 4 times moreadenomasat risk of malignant transformation.

Remember that colorectal cancer is the second most common cancer in women behind breast cancer, and it ranks third in men, behind prostate and lung cancer. Its importance justifies the establishment of a large-scale screening test in most Western countries. In France, the test is systematically offered (by mail) from the age of 50, and up to 74, every 2 years. In Quebec, on the other hand, this screening is not yet systematic.

The immunoassay is based on the detection of blood in the stool through the use ofantibody that recognize and cling to hemoglobin (the pigment in red blood cells).

It is easy to use because it only requires one stool collection. In practice, it is necessary to place a paper (provided) on the toilet seat to collect the stools, and use the device provided (a rod) to collect a stool sample. The rod is then returned to the tube, and the tube must be mailed (with the identification sheet) no later than 24 hours after the test has been performed.

The test is 100% covered by Social Security.

The results are sent by mail or by internet within 15 days of sending. In 97% of cases, the test is negative: no presence of blood is detected.

Otherwise, it will be necessary to consult your doctor to undergo a colposcopy (examination of the entire lining of the colon using an endoscope) to ensure the absence of colorectal cancer.

Note that some polyps or cancers do not bleed when the samples are taken and are therefore not detected by the test. The patient will receive an invitation to repeat the screening two years later. If before these two years, the person has digestive disorders (presence of blood in the stool, sudden change in transit, or persistent abdominal pain), it is advisable to consult a doctor who can establish a diagnosis.