First, the formation of intestinal polyps are mainly due to the following reasons.
1, infection: inflammatory polyps are associated with chronic inflammation of the intestine.
2, age: the incidence of colorectal polyps increases with age.
3, embryonic abnormalities: juvenile polyposis is mostly misshapen tumors, which may be related to abnormal embryonic development.
4, lifestyle habits: low-fiber diet is associated with colorectal polyps; smoking is closely related to adenomatous polyps
5, genetic: the occurrence of certain polyposis is related to genetics, such as familial non-polyposis colorectal cancer (HNPCC) and familial adenomatous polyposis (FAP).
High-risk groups include: family members with colon cancer or colon polyps; long-term eaters of high-fat, high-animal-protein, low-fiber and fried foods; and people older than 50 years old. In addition, the longer you sit, the higher the risk of developing intestinal polyps. It is recommended that these types of people have an annual examination such as electronic colonoscopy, anal finger examination and fecal occult blood to detect colon adenomas with cancer tendency in time. In Europe and the United States, where colorectal cancer is highly prevalent, from the age of 50, it is recommended for all people to have an annual occult blood test on naturally excreted stool and a complete colonoscopy every 5 to 10 years for early detection.
Second, polyps can become cancerous?
First, we must clarify the premise that not all polyps can become cancerous. Generally speaking, we will classify intestinal polyps into non-neoplastic polyps and adenomatous polyps (also called neoplastic polyps).
Non-neoplastic polyps are generally less likely to become cancerous and mainly include.
1, juvenile polyps: commonly found in young children, mostly under 10 years old. They often occur in the rectum, are round and spherical, mostly solitary, and are pathologically characterized by retention cystic cavities of varying sizes, which are a kind of misshapen tumor.
2.Inflammatory polyp: also known as pseudopolyp. Is the ulcer of the large intestinal mucosa in the healing process of fibrous tissue hyperplasia and ulcer submucosal edema, so that the normal mucosal surface gradually elevated and formed. It is commonly found in chronic ulcerative colitis, amebic dysentery, schistosomiasis, intestinal tuberculosis and other intestinal diseases.
Adenomatous polyps are recognized as precancerous lesions. Adenomatous polyps can be divided into three types, namely, tubular adenoma, villous adenoma and tubular choroidal adenoma, among which tubular adenoma is the most common.
How long does it take for a polyp to become cancerous?
In terms of age of onset, adenomatous polyps are 5 to 10 years earlier than colorectal cancer. According to the theory of adenoma to cancer development published by Morson in 1976, this time is about 10 years. However, according to some recent literature, it takes at least 5 years to develop from adenomatous polyps to cancer, with the average being 5 to 10 years. In addition adenomatous polyp carcinogenesis is related to its size, morphology and pathological type. Broad-based adenomas have a higher rate of carcinogenesis than ciliated adenomas; the larger the adenoma, the greater the likelihood of carcinogenesis; and the more villous components in the adenoma structure, the greater the likelihood of carcinogenesis. The specific mechanism of transformation from adenoma to cancer is unknown, but from the perspective of molecular biology, the accumulation of multiple mutations in oncogenes (e.g., APC gene, K-ras gene, etc.) and oncogenes in colonic mucosal cells forms the biological basis of pathological changes.
There are also some special types of adenomatous polyps: flat polyps and lateralized developmental polyps.
Flat polyps
refers to adenomas that are flat or slightly elevated on the surface of the colonic mucosa and whose adenomatous component is no more than twice the thickness of the surrounding normal mucosa. It has been reported that the proportion of flat adenomas with severe heterogeneous hyperplasia exceeds that of the usual raised polyps. The abnormal expression of p53 and p21 in flat adenomas suggests that the biological behavior of small flat adenomas of the colon is different from that of polypoid adenomas of the colon. The larger the size of polypoid adenoma of the large intestine, the more obvious its malignant tendency. However, flat adenomas may become malignant at an early stage and become flat-type early colorectal cancer.
Lateral developmental colon polyp (LST)
It rarely invades the deeper layers of the intestinal wall, but mainly spreads laterally and superficially along the mucosal surface, also known as proliferative tumors and precancerous lesions. At the early stage of growth, because there is no obvious difference between them and the surrounding mucosa, the mucosal surface is only slightly congested, rough or small granular elevation, so the diagnosis is often missed under endoscopy. However, mucosal staining with indigo carmine or methylene blue can help improve the diagnosis rate. Some dynamic studies have shown that its benign lesions can develop into progressive colorectal cancer within 3 years, so early diagnosis and treatment of LST can reduce the risk of colorectal cancer.
Fourth, in clinical work, the treatment plan is generally decided according to the size, number, presence of complications and pathological nature of intestinal polyps.
1.Small polyps are usually removed during colonoscopy and sent for pathological examination.
2.Adenomas with diameter >3cm, especially villous adenomas, should be surgically removed: those below the peritoneal fold should be removed through the anus, while those above the peritoneal fold should be removed openly or under laparoscopy.
If the adenoma penetrates the mucosal muscle layer or infiltrates the submucosa, it is invasive cancer and should be treated according to the treatment principle of colorectal cancer. If the adenoma malignant lesion does not penetrate the mucosal muscle layer, does not invade the small blood vessels and lymph, has a good differentiation degree, and has no residue on the cutting edge, it is not necessary to do surgery after removal, but should be closely observed.
4, inflammatory polyps to treat the primary intestinal disease, inflammatory stimuli disappear, polyps can disappear on their own; proliferative polyps symptoms are not obvious, no special treatment.
Intestinal polyps are not a major disease, but they should not be ignored. For polyps in colonoscopy report, we can neither ignore nor need to be overly alarmed. For recurrent polyp growths, we must pay attention to the possibility of genetic diseases and also to the presence of other diseases. For patients who are found to have intestinal polyps but do not need special treatment for the time being, they must pay attention to their daily diet and have regular colonoscopies.