They must be screened at all costs to detect colorectal cancer in time, what are polyps ?

Cancer colorectal : qu’est-ce qu’un polype ?

Une question surgit à l’occasion de Mars bleu, le mois du cancer colorectal : qu’est-ce qu’un polype intestinal ?

Performing a colonoscopy makes it possible to detect the possible presence of polyps in the colon and rectum and to remove them before they turn into cancer. Because in more than 80% of cases, colorectal cancer comes from a benign tumor – the polyp – which progresses slowly and eventually becomes cancerous.

Most polyps develop incognito inside the colon and rectum, without any symptoms perceptible to the individual. For this reason, a screening test has been developed: the fecal immunological test (FIT) is capable of detecting the slightest trace of blood in the stool, the most common indicator of the presence of polyps.

If the immunological test comes back positive, in 4% cases, the person must then undergo a colonoscopy. Some people whose risk of colorectal cancer is very high are immediately referred to a colonoscopy, without going through the "FIT" box.

Colonoscopy, a "2 in 1"

"If polyps are identified during the colonoscopy, the continuation of the operations depends on their size, appearance and number, specifies Dr Bertrand Brieau, head of the "Cancer screening and prevention" commission; of the French Society of Digestive Endoscopy (SFED). Because in addition to exploring the walls of the colon and rectum, colonoscopy allows the removal of the polyp or cancer." Then, the removed polyps are sent to the laboratory for tissue analysis (histological analysis), in order to assess the level of risk of new polyps occurring and to adapt surveillance.

3 types of colorectal polyps

Polyps are benign tumors, which can be compared to warts that grow on the inner lining of the colon and rectum. These lesions grow slowly, taking about a decade before becoming cancerous. Three main types of polyps can be identified. First of all, the "hyperplastic polyps", which are benign and never degenerate. Then, "adenomas", which are the most common polyps, likely to develop into colon cancer. Finally, a newer intermediate class is known as “scalloped polyp”, and which is also associated with colon cancer. "This last category of polyps are flat lesions more difficult to detect, points out Bertrand Brieau, but recent advances in the use of high definition endoscopes has improved their detection. "

New techniques for removing polyps

In recent years, endoscopic resection techniques for precancerous or early cancerous lesions have replaced the surgical approach for the removal of large polyps and superficial colorectal cancer. Surgery (we remove the part of the colon where the polyp or cancer is located) remains necessary for polyps that have progressed to invasive cancer, that is to say cancer that has deeply infiltrated the wall of the colon.

Mucosectomy (removing part of the lining of the colon wall on which the polyp grows) makes it possible to remove polyps measuring between 10 and 20-25 mm. Beyond this size, or when the polyp is suspected of being cancerous, new techniques such as submucosal dissection are becoming increasingly necessary, allowing polyps to be removed without size limits. To understand this new technique, an image is telling: we can compare the wall of the digestive tract to a house wall with wallpaper (mucosa), a coating (submucosa) and bricks (muscle). In submucosal dissection, to increase the working surface, liquid is injected into "the’coating" (through the "wallpaper") to inflate it and move the wallpaper away from the bricks to be protected. We can then cut into the submucosal layer to remove the polyp, without perforating the colonic wall.

AI-assisted endoscopy, it’s already tomorrow

The "augmented colonoscopy" thanks to artificial intelligence (AI) is arriving in operating theaters. A visual signal (a colored square), accompanied or not by an audible signal, appears around the detected polyp, when the gastroenterologist passes his endoscope into the intestine. "L’IA allows the increase in the detection rate of adenomas from 10 to 15%, estimates Dr. Brieau. This technology is an aid for the practitioner, by signaling potential lesions which could escape the human eye, due to fatigue, the difficulty of spotting them or for those who are just starting out."

In addition to identifying polyps, AI is now able to characterize in real time the types of polyps detected (so that the gastroenterologist can make an informed decision at the time whether to remove them or not ), to identify other anomalies (ulcerations, vascular lesions…) and even to check the quality criteria of the endoscopic examination.