Colon polyps and polyposis

　　First, the causes of onset

　　Long-term intake of high-fat, high-protein, and low-fiber diets significantly increases the incidence of colonic and rectal polyps. The incidence of polyps decreases with the intake of fresh fruits, vegetables, and vitamin C.

　　In patients with gastric duodenal ulcer undergoing gastrojejunal anastomosis and cholecystectomy, the flow and excretion time of bile change, and the content of bile acids in the large intestine increases. Experiments show that bile acids and their metabolites, such as deoxycholic acid and lithocholic acid, have the effect of inducing adenomatous polyps or canceration in the colonic mucosa.

　　In colorectal cancer patients, about 10% of patients have a family history of cancer. Similarly, when someone in the family has adenomatous polyps, the other members have a significantly higher risk of developing colonic and rectal polyps, especially in familial polyposis, which has a significant familial genetic component. In addition, patients who have had cancer in other parts, such as gastrointestinal cancer, breast cancer, uterine cancer, and bladder cancer, also have a significantly higher incidence of colonic and rectal polyps.

　　The chronic inflammatory lesions of the colonic mucosa in intestinal inflammatory diseases, such as ulcerative colitis, Crohn's disease, amebiasis, intestinal schistosomiasis, and tuberculosis, are the main causes of the occurrence of inflammatory polyps. They are also seen in the anastomotic site after colonic surgery.

　　The occurrence of familial adenomatous polyposis may be related to the loss of function and absence of a tumor suppressor gene called APC (adenomatous polyposis coli) located on the long arm of chromosome 5. Normally, this allele gene needs to function simultaneously to inhibit tumor growth. When the gene is absent or mutated, the inhibitory effect on tumors disappears, leading to adenomatous polyposis of the colon and rectum and canceration.

　　Second, pathogenesis

　　1, Colon polyps

　　（1）Adenoma: According to American autopsy data, 22% to 61% of the population can be found with adenomas. According to fiberoptic colonoscopy examination of the general population without family history, personal history, or symptoms, the rate is 25% to 41%. From the epidemiological data of immigrants, the incidence of adenomas increases, indicating that environmental and lifestyle changes are related. Adenoma occurrence is more common in males than in females, and increases with age. According to autopsy data, the incidence rate of adenomas before the age of 50 is 17%, 35% for ages 50 to 59, 56% for ages 60 to 69, and 63% for those over 70. It is generally believed that colorectal cancer originates from adenomatous polyps, with a cancerous rate of 1.4% to 9.2%, and removal can reduce the risk of colorectal cancer.

　　2, Pathological morphology

　　(1) Early classification: Early colonic adenomas can be divided into 4 types:

　　① Small flat adenoma: It is a tubular adenoma-like image, with thickened mucosal lesions, atypical epithelium involving the affected mucosal part, extending outward rather than vertically downward to the base.

　　② Small depression adenoma: The mucosal凹 area呈管状腺瘤 structure, can occupy the entire mucosal layer.

　　③ Microscopic adenoma: The tubular adenoma that involves the entire adenotube and can only be found under a light microscope.

　　④ 'Saw-tooth' adenoma: Adenomas with both proliferative polyp and tubular adenoma images, about 2/3 of the tumor volume is less than 1 cm.

　　(2) Maturity classification: Pathologically divided into 3 categories:

　　① Tubular adenoma: Also known as adenomatous polyps or polypoid adenomas, they are hemispherical or elliptical, with a smooth or lobulated surface, pink or gray-red in color, with possible congestion, edema, and erosion. The diameter of polyps is small from 1 cm to large as 5 cm, most of which are above 1 cm in clinical findings, with larger ones often having a pedicle, a few (15%) broad-based or pedicleless.

　　② Villous adenoma: Also known as papillary adenoma, accounting for 10% to 20%. Generally, they are larger in size, mostly broad-based or with a wider base, and those with a pedicle are usually smaller, with a cancerous rate of 30% to 40%.

　　③ The proportion of tubular villous adenoma components is similar, but part of the adenoma surface is smooth and part is rough, with a larger volume.

　　2, Juvenile polyps and polyposis: Juvenile polyps, also known as congenital polyps, retention polyps, or juvenile adenomas, are common in children, but can also be seen in adults, mostly under the age of 10, with more than 70% being solitary, but can also be multiple (usually 3 or 4), 60% occurring within 10 cm from the anal rectum. In the 2 adult surveys in Haining County, Zhejiang Province, juvenile polyps accounted for 6.2% to 7.2% of all polyps. The appearance of polyps is mostly spherical, with a smooth, pink surface, visible erosion, and covered with dirty exudate. The cross-section shows varying sizes of retention cysts filled with mucus. Under the microscope, the adenotubes are arranged in a scattered manner, with some adenotubes highly expanded into cysts, lined with flat epithelium, containing shed epithelial cells and inflammatory cells, with abundant stroma and a large amount of inflammation and congestion.

　　3. Inflammatory polyps (inflammatory polyps): There is obvious infection, non-neoplastic, with ulceration and degeneration, including Crohn's disease or ulcerative colitis, etc. Inflammatory polyps can be classified into 2 types:

　　(1) Multiple or single polyps are composed of inflammatory stroma or granulation tissue and hyperplastic epithelium;

　　(2) Related to mucosal inflammatory diseases, also known as pseudopolyps, such as ulcerative colitis, Crohn's disease, schistosomal granuloma, etc. The lesions around these diseases show polypoid appearance and can also occur at the anastomotic site of intestinal surgery, or at the inflammatory polyps at the edge of ulcers.

　　1. Anemia:Due to the erosion, ulceration, or inflammation of the surface of the polyps, leading to intestinal bleeding, patients may present with coffee-colored stools, black stools, or hematochezia. Some patients may have small amounts of bleeding multiple times, with hemoglobin dropping to 5g, which becomes the main reason for seeking medical attention.

　　2. Malignancy:Inflammatory polyps formed by schistosomiasis, Crohn's disease, and familial polyposis are all related to the degree of colonic carcinogenesis. According to Weedon's statistics, the incidence of colorectal cancer in Crohn's disease is 20 times higher than that in the control group. The incidence of colorectal cancer is also high in areas with schistosomiasis. In 1882, Cripps described the potential for malignant transformation of familial polyps, which was basically confirmed by Hauser's research and literature review, indicating the tendency of polyposis to malignant transformation.

　　More than half of the polyps have no clinical symptoms and are often discovered during general health checks or autopsies, or when complications occur. The symptoms are summarized as follows:

　　1. Intestinal irritation symptoms:Diarrhea or increased frequency of defecation, in severe cases, can lead to electrolyte and water imbalance, and in cases of infection, mucous bloody stools may be seen.

　　2. Hematochezia:It can be of varying degrees of hematochezia, such as: rectal bleeding from lower rectal polyps can be seen as bloodstains on feces, high-grade polyps bleeding is often mixed with blood or clots in the feces, and in cases with large amounts of bleeding, fresh blood or clots can be passed directly, or there may be bleeding after defecation.

　　3. Intussusception or associated with intestinal obstruction:This is caused by the polyps themselves, and even polyps may be seen protruding from the anal orifice, which is often seen in children and can fall off or retract on their own.

　　4. Signs:Abdominal examination may reveal palpable masses associated with tenderness, mostly belonging to intussusception of intestinal loops, with hyperactive bowel sounds, etc. It may also show no obvious abdominal signs. In patients with melanosis coli, spots of pigmented沉着 can be seen on the oral mucosa, lips, perioral area, perianal area, and the palm and sole of both hands.

　　虽然腺瘤可发生出血或少量出血，但常常可无症状，定期大便隐血试验(FOB)可以发现阳性，对此类患者作进一步纤维结肠镜或X线气钡造影能达到隐血阶段腺瘤的诊断，然而并非腺瘤均会发生或少量隐血，1/3～1/2腺瘤并无出血，结合高危因素的序贯筛检及其优化方案是可以弥补以FOB筛查之不足。

　　1. The basic principle of the treatment of familial adenomatous polyposis is to remove the affected intestinal tract before the polyps become cancerous and to carry out general screening and follow-up for family members. Careful registration of the family tree is very important for the discovery of high-risk populations. For children in the family, regular colorectal examinations should be carried out after the onset of puberty, usually once every six months, until the age of 40. If there are no polyps in the colon and rectum by then, the chance of developing polyps again is relatively low. However, it is noteworthy that a few patients may still develop polyposis after the age of 60. In addition, regular examinations of the upper gastrointestinal tract should also be carried out, especially around the ampulla of Vater, to exclude the possibility of polyps in the duodenum and around the ampulla.

　. 　1. Fecal occult blood test (FOBT)

　　The overall detection rate of polyps is relatively low, and some new FOB detection methods have been developed in recent years. Zheng Shu et al. reported in 1991 that the use of reverse indirect hemagglutination assay fecal occult blood test (RPHA-FOBT) and computer risk assessment, combined screening of colorectal cancer in the population, found that the sensitivity and specificity of the RPHA method are both high, and this method has a certain detection rate of colorectal polyps (21.1%), and the size of the polyps is closely related to bleeding, the detection rate of bleeding in polyps with a diameter greater than 1cm reaches 43.5%, and the positive rate of FOB in adenomas with a high malignant tendency increases. The RPHA-FOB positive rates of tubular, tubulovillous, and villous adenomas are 17.8%, 30.0%, and 45.5%, respectively.

　　2. Tumor marker detection

　　For example, single-chain monoclonal antibodies and immunohistochemical techniques are used to determine tumor-related antigens such as MC3, CA19-9, CEA, CA50, and others in tumor tissues; the DNA content of tumor tissues or the analysis of DNA ploidy levels are determined using flow cytometers or microspectrophotometers, etc. Abnormalities in these indicators are believed to be related to cancer occurrence, and some indicators appear before morphological changes, which can be used for the monitoring of early cancer changes, cancer progression, and early recurrence. However, the detection of adenomas is still mainly in the research stage at present, and the prospect of clinical wide application needs to be observed.

　　3, Rectal examination

　　It is the simplest and most reliable method for examining the lower intestine within 7 to 8 cm from the anus. Feeling a hard mass is a reliable indicator of polyp malignancy, but if the polyp is located higher, rectal palpation often cannot feel it.

　　4, Sigmoidoscopy

　　It is the main method for examining low-positioned colonic and rectal polyps, and can often complement the barium enema method.

　　5, Barium enema

　　It is not easy to detect smaller polyps, especially for low-positioned or lower rectal polyps. Double-contrast barium enema can improve the detection rate of polyps and reduce misdiagnosis caused by intestinal cavity bubbles. Patients with polyps >0.5 cm found by sigmoidoscopy need to undergo further barium enema and colonoscopy of the proximal colon, often finding simultaneous colon lesions. Single-contrast barium enema has lower sensitivity to proximal intestinal polyps than double-contrast, so patients with adenomas found by sigmoidoscopy should undergo further examination, starting with colonoscopy. If the entire colon cannot be examined, then double-contrast barium enema examination should be chosen.

　　6, Colonoscopy

　　It is currently the most accurate and reliable method for diagnosing colonic and rectal polyps. Operators with skilled techniques can reach the ileocecal region in more than 90% of cases, and can make certain estimates of whether polyps have become cancerous. It is reported that the use of dye marking under endoscopy can detect tubular adenomas and villous adenomas. In recent years, there have been many reports on the indications for colonoscopy from abroad. There are reports that 10% to 25% of people over 40 have asymptomatic polyps detected by endoscopy, and a large number of polyps are found outside the reach of the sigmoid colonoscope, up to 60 cm. Therefore, for any patient with a polyp found by sigmoidoscopy, or for patients with recurrent polyps after resection, a full colonoscopy should be performed to detect synchronous cancer or synchronous polyps. About half of the polyps and cancers are missed by barium enema, so it is necessary to perform a full colonoscopy before colorectal cancer surgery to promote the detection of synchronous tumors and reduce the incidence of early synchronous cancer and adenoma cancer. Currently, some abroad advocate that all patients who have undergone adenoma resection should undergo long-term, periodic colonoscopy, but some do not agree, believing that the risk of dying from cancer after a single small adenoma is very low.

　　7, Colon ultrasound

　　It is a method of using ultrasound to continuously scan the rectum and sigmoid colon after retrograde lavage of the colon. This method is sensitive, economical, reliable, and has no side effects. The report can thoroughly examine all segments of the rectum and sigmoid colon, detect most polyps and cancers. There are reports that the sensitivity to polyps larger than 0.7 cm is 91%, with no false positives.

　　Consuming foods rich in calcium, including milk and other dairy products, as well as cauliflower; appropriately consuming some animal liver, egg yolks, fish, and dairy products fortified with vitamin D; eating more fruits, vegetables, and whole grains. Eating more foods rich in vitamins. The adequacy of vitamin content in the human body is closely related to people's health, being interrelated. It is also necessary to avoid eating large amounts of fish, meat, and overly greasy foods to prevent the middle jiao from being constrained, leading to poor transformation and nutrition.

　　First, treatment

　　Since it is difficult to judge the nature of polyps with the naked eye, it is generally recommended to remove them surgically or take a sample for pathological diagnosis after discovery. Different treatment plans are chosen due to the size, number, pedicle or non-pedicle, and nature of the polyps or adenomas located at different sites:

　　1. Surgical methods

　　(1) Loop coagulation method: First, suck out the mucus and fecal water attached to the surrounding polyps, withdraw and inject air to displace hydrogen, methane, and other gases that may be present in the intestines to prevent explosion during electrocoagulation. Bring the loop suture close to the polyp, avoid making the loop too close to the intestinal wall to damage it and cause fatal perforation. After inserting the loop, tighten the suture, select different current power according to the thickness of the pedicle, and cut slowly to ensure complete hemostasis.

　　(2) Biopsy forceps coagulation method: For 0.5 cm wide-base lesions, use biopsy forceps to grasp the entire lesion, lift it to make the base into a curtain-like narrow false pedicle, then pass the current for a few seconds to make the local area turn grayish-white, and then bite tightly with the biopsy forceps to pull down the tissue for pathological examination.

　　(3) Electrocoagulation method: This method is mostly used for lesions less than 0.5 cm in size, which are mostly benign. For those that cannot be removed by clipping, the electrocoagulation hemostat can be used to contact and burn the lesion with coagulating current. However, do not go too deep to avoid perforation or delayed perforation, which can occur 2 to 7 days after surgery.

　　(4) Surgical treatment: The surgical treatment of polyps and polyposis generally includes: local resection, resection of the intestinal wall, resection of the intestinal segment, subtotal colectomy or total colectomy with rectum resection. It depends on the number of polyps, whether they have a pedicle and their location: ① Polyps with pedicles are removed by endoscopic ligation, electrocoagulation (coagulation) or ligation. For those with a large volume, it is difficult to perform ligation resection or incisional resection, and intestinal wall or intestinal segment resection can also be chosen. ② Polyps without pedicles or broad pedicles located below the peritoneal fold are removed locally, while those above the fold are resected by incising the intestinal wall including the base of the intestinal wall or resecting the intestinal segment. ③ Adenomatous polyposis, including familial, non-familial, and Gardner and Turcot diseases, have numerous intestinal tumors that are prone to cancer and occur at an early age. For example, familial adenomatous polyposis usually develops into cancer before the age of 50, so it is advocated to perform total colectomy with rectum resection and ileostomy, but it brings lifelong inconvenience to younger patients, so some people advocate total colectomy with ileorectal anastomosis. Whether the remaining rectum is the source of cancer, the StMark data shows that only 6.5% develop rectal cancer after 25 years of follow-up, and most are early-stage, so strict follow-up after surgery is necessary. Recently, some people advocate partial resection of the rectum in addition to mucosal stripping of the remaining rectum, preserving the lower rectal muscular canal, and direct anastomosis between the ileum and the lower segment of the rectum. In summary, preserving anal function, although it adds some difficulty to surgery, can avoid lifelong ileostomy and is more easily accepted by patients.

　　2, Surgical selection

　　(1) Endoscopic resection of pedunculated and sessile polyps: Pedunculated polyps are removed simultaneously with snare resection during colonoscopy, small sessile polyps can be removed by electrocoagulation, and large ones can be injected with normal saline submucosally. Common complications after snare electrocoagulation resection are postoperative hemorrhage, 0.1% to 0.2%.

　　(2) Follow-up once a year for 1 to 3 years, including for patients with progressive adenoma in situ carcinoma or highly atypical hyperplasia. Since adenoma polyps have lymphatic vessels贯穿ing the muscularis mucosae, those with severe atypical hyperplasia and carcinoma change are all limited to the mucosa without lymph node metastasis.

　　(3) Pedunculated polyps can be removed by snare resection. The treatment for sessile polyps is: ①

　　(4) Surgical resection:绒毛状广基腺瘤 diameter >2cm is not suitable for piece-by-piece resection via colonoscopy and should be removed surgically. Those located above the peritoneal reflexion cannot be removed via endoscopy and should be treated as colorectal cancer, as more than one-third of such patients have invasive carcinoma; those that can be removed via endoscopy require careful pathological examination after resection. If invasive cancer is found, radical surgery should be performed again. Those located below the peritoneal reflexion can be locally resected via anal or sacral approach.

　　(5) Principles of treatment for adenoma carcinoma:

　　①Carcinoma in situ limited to the mucosal layer: It is universally recognized that local resection is sufficient, but pathological confirmation is required.

　　②Malignant polyps: As adenomas with cancerous invasion, they involve the mucosa and submucosa. Colonoscopy-assisted resection is prone to residual disease and lymph node metastasis, so it is advocated that patients confirmed to have malignancy should undergo reoperation. Small flat polyps can be removed first, and if suspicious of malignancy during endoscopic examination, surgical resection is required. Therefore, Indiaink is locally injected during endoscopic removal, and marked for further surgery after pathological confirmation. Follow-up for 3 to 6 months after the removal of malignant tumors, reoperation is required if recurrence occurs.

　　③Invasive cancer: When the canceration penetrates the submucosal layer, there is no unified treatment opinion. The choice of surgical method mainly depends on the risk of cancer metastasis and recurrence. A total of 347 cases of invasive cancer were comprehensively analyzed from the literature, with a total lymph node metastasis rate of 9%, among which the metastasis rate of malignant changes in sessile adenomas is 15%, and the rate of residual cancer is 6%. The metastasis rate of pedunculated adenomas is 7.8%, among which the rate of residual cancer is 2.3%. When the cancer is limited to the pedicle or the head of the adenoma, the lymph node metastasis rate is 3%, while when the cancer enters the neck or base, the lymph node metastasis rate is 20%.

　　⑤ Adenoma cancer invasion into the muscular layer: It is generally believed that radical surgery is required regardless of differentiation. However, some people have reported that for rectal cancer at the T2 stage of the lower rectum, local resection combined with radiotherapy can achieve satisfactory results.

　　Second, prognosis

　　1. Polyposis has a significant tendency to become cancerous. Lockhart-Mummcry once predicted that 'every polyposis patient, if left to develop naturally, will eventually develop into cancer. Simple polyposis is mainly distributed in the rectum and sigmoid colon, with the largest polyp diameter of 4cm, all of which have become cancerous. The cancerous rate is 36% (Hullsiek) or 73% (Dukes) when patients seek medical attention due to worsening symptoms. The tendency to become cancerous is believed to be related to an increased sensitivity of genetic variation to carcinogens.

　　2. The length of the course is positively correlated with the cancerous rate of polyps. Muto statistically analyzed the cancerous condition of 59 patients, and the cancerous rate was 12.7% for those with a course of 5 years or less, 41.8% for those with a course of 5 to 10 years, and a higher cancerous rate for those with a course of more than 10 years (45.4%). There were 4 cases in this group of cases that had not been found to have cancerous changes after 20 years.

　　3. Cancerous changes are related to age. This disease often occurs around the age of 20, and those who develop the disease before the age of 10 or after the age of 40 are rare. The age of cancerous changes is usually after the age of 30, 10 to 20 years earlier than the general population. After analyzing a large group of cases, Dukes believed that the average interval from onset to diagnosis of cancerous changes is 8 to 15 years. By age group analysis: the cancerous rate is 29% for those under 19 years old, 38% for those aged 20 to 29, 82% for those aged 30 to 39, and 92% for those aged 50 to 59.

　　4. Cancerous changes in polyps often occur multicentrically, and there are many cases of rectal and sigmoid colon cancer. These characteristics should be noted during clinical biopsy.

　　Simple polyposis has a tendency to form polyps again in the large intestinal mucosa that remains after surgery or electrocoagulation treatment. The polyps that re-form are called 'recurrent polyps'. Jackman found in a follow-up of 56 postoperative cases that 70% can develop recurrent polyps, of which 12.5% develop into cancer. In recent years, it is more and more advocated to perform total colectomy. However, by 1962, there were also 10 cases of spontaneous regression of simple polyposis reported in the world, the mechanism of which was unclear.