Colon adenoma

　　Colon adenomas are a precancerous lesion, manifested as irregular protrusions on the colon mucosa, which can be divided into pedunculated and broad-based types. The histological sections can show varying amounts of villous components. Adenomas are divided into tubular adenomas (villous components accounting for less than 20%), mixed adenomas (villous components accounting for 20% to 80%), and villous adenomas (villous components accounting for more than 80%) according to the proportion of villous components in adenomas. Clinically, tubular adenomas are the most common, accounting for about 70%. Due to its classification characteristics, it is only possible to determine the histological type of adenoma after pathological examination of the complete adenoma tissue. Although most colorectal cancers originate from colon adenomas, not all colon adenomas lead to canceration. The canceration of adenomas is related to the following factors.

　　1. Generally speaking, the chance of canceration of adenomas increases significantly with the increase of adenomas.

　　2. In the pathological type of adenomas, the more the villous component, the more likely it is to become cancerous. Villous adenomas have the highest cancerous rate, followed by mixed adenomas, and tubular adenomas have a lower cancerous rate.

　　3. The cancerous rate of broad-based adenomas is significantly higher than that of pedunculated adenomas.

　　4. The atypical hyperplasia degree of adenomas increases significantly with the increase of atypical hyperplasia degree, with an incidence rate of about 5.7% for mild atypical hyperplasia, 18% for moderate, and 34.5% for severe.

　　Patients with colon adenomas often have concurrent diseases such as hematochezia, colon polyps, intussusception, or accompanying intestinal obstruction, as follows.

　　1. Hematochezia:It can be varying degrees of hematochezia.

　　2. Intussusception or accompanying intestinal obstruction:Large pedunculated adenomas can cause intussusception or accompany intestinal obstruction.

　　3. Colon polyps:Also, symptoms such as hematochezia, changes in defecation habits, and abdominal pain may occur, which are easily confused with colon cancer, but colonoscopy and histopathological examination can help differentiate.

　　4. Appendiceal abscess:There may be a history of acute or chronic appendicitis or right lower quadrant abdominal pain, with right lower quadrant tenderness and abdominal muscle tension, elevated peripheral blood count, and abdominal ultrasound or CT examination may reveal a fluid mass in the lower abdomen. Colonoscopy or barium enema X-ray examination can exclude cecal tumor.

　　The symptoms of colonic adenoma are related to its size and location. Small adenomas often have no symptoms, while the symptoms of larger adenomas can be summarized as follows:

　　1. Hematochezia:It can be different degrees of hematochezia, such as less bleeding or when the adenoma is located in the right half of the colon, it is often not easily noticed by the naked eye, and the fecal occult blood test may be positive.

　　2. Intestinal stimulation symptoms:It is manifested as diarrhea or an increase in the frequency of defecation, which is more common in villous adenomas.

　　3. Intussusception or intestinal obstruction:Large pedunculated adenomas can cause intussusception or intestinal obstruction, leading to abdominal pain.

　　To prevent colonic adenoma, it is important to develop good living habits, quit smoking, and limit alcohol consumption. The World Health Organization predicts that if people stop smoking, the world's cancer rate will decrease by 1/3 in 5 years; smoking and alcohol are highly acidic substances, and people who smoke and drink for a long time are prone to acidic constitution. Avoid eating too much salty and spicy food, and do not eat overheated, cold, expired, or deteriorated food; for the elderly, the weak, or those with a genetic predisposition to certain diseases, eat some cancer-preventive foods and alkaline foods with high alkaline content, and maintain a good mental state.

　　Colonic adenoma should undergo biopsy, fecal occult blood test, rectal examination, X-ray examination, and other examinations, as specified below.

　　1. Biopsy:Multiple or repeated sampling should be done, and it is best to remove the polyps completely for examination to increase the positive rate of diagnosis.

　　2. Fecal occult blood test:Its diagnostic significance is limited, with a high number of false negatives, and positive cases can provide clues for further examination.

　　3. Rectal examination:It is the simplest and most reliable method to check the rectum within 7-8 cm from the anal opening. The presence of a hard mass is a reliable indicator of adenoma malignancy.

　　4. X-ray examination:Barium enema X-ray examination is not easy to detect smaller adenomas, and it is difficult to display low-position adenomas, especially rectal adenomas. Double-contrast barium enema can improve the detection rate of adenomas.

　　5. Endoscopic examination:Including rectoscopy, sigmoidoscopy, and fiberoptic colonoscopy, which are currently the most reliable examination methods, but there is still a possibility of missed diagnosis. All polyps found during endoscopic examination should be biopsied. Adenoma malignancy often appears as an enlargement of the adenoma under the endoscope, with symptoms such as erosion, ulceration, and necrosis on the surface, broad base or short pedicle, and the base of subpedunculated adenoma is rigid, and the fragility of the adenoma tissue increases, and so on.

　　In addition to general treatment, patients with colonic adenoma should also pay attention to dietary regulation.

　　1. Eat less or avoid foods rich in saturated fat and cholesterol, including lard, butter, fatty meat, animal internal organs, fish roe, and so on.

　　2. Limit vegetable oils to about 20-30 grams per person per day (approximately 2-3 tablespoons).

　　3. Avoid or eat less fried food.

　　4. Eat foods containing unsaturated fatty acids in moderation, such as olive oil, tuna, and so on.

　　5. Supplement more than 35 grams of dietary fiber per day.

　　6. Consume more foods rich in dietary fiber: konjac, soybeans and their products, fresh vegetables and fruits, algae, and so on.

　　7. Replace some coarse grains with fine grains.

　　8. Eat more fresh vegetables and fruits to supplement carotene and vitamin C.

　　9. Eat moderate amounts of walnuts, peanuts, dairy products, seafood, etc., to supplement vitamin E.

　　10. Pay attention to consuming foods rich in trace element selenium such as malt, fish, mushrooms, etc.

　　Colorectal adenomas are precancerous lesions, and they should be treated promptly upon discovery. Most adenomas can be resected under the microscope, and if the colonoscopy cannot be used (usually for villous broad-based adenomas with a diameter greater than 2cm), surgical resection should be performed. No further treatment is needed for those without cancer after postoperative pathological examination; for those with cancer, different treatment methods should be chosen according to the depth of invasion.

　　1. Underoscopic resection

　　Underoscopic resection Methods of underoscopic resection include loop coagulation, biopsy forceps coagulation, and electrocoagulation. Loop resection can be performed for pedunculated adenomas, and biopsy forceps coagulation or electrocoagulation can be used for broad-based adenomas less than 0.5cm, and loop coagulation can be used for those between 0.5cm and 1cm.

　　2. Surgical resection

　　Villous broad-based adenomas with a diameter greater than 2cm should not be resected in pieces through colonoscopy and should be surgically resected, generally following the principles of colorectal cancer surgery.

　　3. Treatment of adenoma cancer

　　1. If the cancer is limited to the mucosal layer, local resection is performed, and follow-up colonoscopy is performed after surgery.

　　2. If the cancer invades the submucosal layer but does not reach the固有muscular layer, China usually decides the surgical method according to the pathological type of the adenoma.

　　(1) Tubular adenomas: If there is no cancer at the cutting edge, or no blood vessels and lymphatic vessels involved in the sections, or good differentiation of cancer cells, or pathological examination confirms complete resection of the adenoma, local resection and close follow-up are generally sufficient.

　　(2) Villous adenomas: Due to the possibility of lymph node metastasis up to 29% to 44%, intestinal resection with lymph node dissection should be performed as in the case of colorectal cancer.

　　(3) Mixed adenomas: If pedunculated, the treatment principle is the same as that for tubular adenomas with invasive cancer limited to the submucosal layer. If broad-based, it is the same as that for villous adenomas with invasive cancer limited to the submucosal layer.

　　(4) For adenomas with invasive cancer to the muscular layer, radical intestinal resection should be performed.