2021年2月2日星期二

hemorrhoids early pregnancy,Colorectal cancer-causes, characteristics, early signs, metastasis, etc.

    Bowel Cancer

    1 What is colorectal cancer

    Colorectal cancer refers to malignant tumors that occur in the colon and rectum. The so-called malignant tumor refers to a local mass with abnormal structure and function formed by the pathological hyperproliferation of local tissue cells in the human body. Clinically, most colorectal cancers grow in the left half, namely the descending colon, sigmoid colon and rectum. Malignant tumors that grow in the transverse colon and the ascending node on the right are relatively rare. With the development of society, the improvement of people's living standards and the change of traditional dietary structure, the incidence of colorectal cancer is increasing.

    2 What is the cause of colorectal cancer?

    The exact cause of colorectal cancer is still unclear, but after years of observation and research, it has been found that some factors are closely related to the occurrence of colorectal cancer. In summary, there are the following: (1) Dietary factors: For example, people with a high-fat, low-fiber diet are susceptible to colorectal cancer. Mildew and pickled food also have the same effect.

    (2) Genetic factors: Some colorectal cancers have obvious genetic tendencies.

    (3) Chronic inflammation of the intestinal tract: For example, patients with ulcerative colitis, Crohn's disease, and intestinal schistosomiasis have a high incidence of colorectal cancer.

    (4) Environmental factors and radiation damage.

    (5) Carcinogenesis of colorectal polyps: At present, colorectal polyps are considered to be a precancerous lesion.

    3. What kind of diet is prone to cause colorectal cancer?

    Scientific research has confirmed that a high-fat, high-protein, and low-fiber diet is positively related to the occurrence of colorectal cancer, that is, people with this diet are susceptible to colorectal cancer. When people eat too much fat, the secretion of bile will increase, because bile is used to digest fat. The bile salts and fatty acids in bile produce large amounts of neutral cholesterol under the action of anaerobic bacteria in the intestine. The degradation products are polycyclic hydrocarbons, which have carcinogenic and auxiliary carcinogenic effects. High protein is mainly animal protein food. During the cooking process, a heterocyclic amine compound with strong mutagenic effect will be produced, which has obvious carcinogenic effect. It is basically clear that saturated fat, especially trans fat, is the main cause of colorectal cancer.

    4. What are saturated fat and trans fat?

    Fat is made up of various fatty acids. It is customary to call fat that is liquid at room temperature as oil, and fat that is solid at room temperature as fat. Whether fat is liquid or solid at room temperature is determined by its saturation. From the point of view of chemical structure, fatty acids are chain carboxylic acids with even number of carbon atoms. Those without double bonds in the carbon chain are saturated fatty acids and are solid at room temperature; those with double bonds in the carbon chain are unsaturated fatty acids and are liquid at room temperature. Unsaturated fatty acids are very beneficial to the human body, but some unsaturated fatty acids cannot be synthesized by themselves and must be ingested from food. These unsaturated fatty acids that are required by the human body but cannot be synthesized by themselves are called essential fatty acids. Too much saturated fat intake will increase the blood triglycerides, which are mainly low-density lipoproteins. It promotes atherosclerosis and aging, and has a certain carcinogenic effect. Trans fat is also called hydrogenated fat. It is made by chemically adding hydrogen atoms to both sides of the unsaturated fatty acid carbon chain during the processing of edible oil. This kind of oil has stable properties and long storage time. Foods cooked with it are bright in color, beautiful, and have a long shelf life. Margarine and refined oil are all trans fats. A survey in the United States showed that saturated fat and trans fat are one of the predisposing factors for breast cancer, colorectal cancer, and cardiovascular and cerebrovascular diseases.

    5. How do harmful fats promote cancer?

    Saturated fat, trans fat, etc. are all harmful fats, which are carcinogens or genetic mutagens. Because they can damage the material basis of normal human cell inheritance--deoxyribonucleic acid, or DNA, induce structural changes in certain genetic genes on the long DNA chain, causing errors in DNA replication or translation, and causing certain Normal cells become "latent cancer cells". When this "latent cancer cell" encounters an opportunity suitable for its development, such as the body's immune surveillance function is reduced, the immune function is weakened, etc., it will divide rapidly and form tumors.

    6 What are the foods with more trans fat?

    (1) Vegetable oils containing trans fats: refined vegetable oils, margarine, chocolate, vegetable cream, ice cream, etc.

    (2) Fried foods: Even if you use vegetable fried foods that do not contain trans fats, the molecules will mutate after the oil is heated at a high temperature for a long time, which is almost trans fat. Therefore, various fried foods also contain more trans fats.

    (3) Various baked foods, such as bread, biscuits, pastries, etc.

    (4) Some seasonings and condiments: such as peanut butter. As long as the packaging is marked with "vegetable oil", "refined vegetable oil" and other words, they all contain a lot of trans fats.

    7 Do you get colorectal cancer if you eat a high-fat diet?

    Epidemiological survey results show that the diets of countries and regions with high incidence of colorectal cancer have the characteristics of polished rice, refined noodles, high fat, high animal protein, and less fiber. The fat content accounts for 40% of the total calories of the diet; colorectal tumors are low The fat content in the diet of developed countries and regions is very low. Japanese fat calories only account for about 12% of total diet calories, and the incidence of colorectal tumors is very low. Of course, people who eat a high-fat diet are more likely to suffer from colorectal tumors than those who eat a low-fat diet; they do not necessarily have colorectal tumors. A high-fat diet must only be an external factor of colorectal tumors. Whether you suffer from colorectal tumors or when you suffer from colorectal tumors mainly depends on the internal aspects of the body. In other words, whether you are suffering from colorectal tumors, internal factors play a decisive role in the body, and external factors are only a condition that promotes the disease.

    8 What are the internal factors that determine whether to develop colorectal cancer?

    In a person's life, whether or not a person suffers from cancer, what kind of cancer, at what time, whether or not metastasis occurs after cancer, and when does metastasis occur, are not determined by carcinogenic factors, but determined by our carrying The sensitivity of the gene’s chromosomes to carcinogens. As the saying goes, "the ten fingers are not the same when they stick out." Not all of our humans' 46 chromosomes are equally healthy. Some chromosomes are inherently weak, just like some people are naturally strong and some people are naturally thin. After these weaker chromosomes are attacked by strong carcinogens, they are susceptible to damage, such as breakage, which causes the genetic genes they carry to mutate and become cancer cells. It is worth noting that this weaker chromosome can be inherited, which also explains why certain families are high-risk groups of certain cancers. Each of us cannot choose our genetic genes. What we can choose is to avoid the attacks of carcinogenic factors as much as possible so that we do not suffer from various cancers as much as possible. As for which chromosome damage will cause humans to develop colorectal cancer, it is still unclear.

    9 What other dietary factors are related to colorectal cancer?

    There are reports in the literature that halides such as chloroform used for disinfection of tap water may also be carcinogens of colon cancer. The incidence of colorectal cancer in people who drink well water is significantly lower than that of people who drink water from rivers and ponds. This may be because the well water is clean water that has been filtered through sand and gravel, and rivers and ponds have been seriously polluted. Researchers also discovered that there is a substance called S-adenosylmethionine in the human body that can inhibit colorectal cancer by affecting DNA. This substance is significantly reduced in alcoholics. Therefore, alcoholism should also be one of the carcinogenic factors of colorectal cancer. In addition, pickled and moldy foods also contain a lot of carcinogens, which also require people's attention. As for whether there is a clear relationship between smoking and the incidence of colorectal cancer, it is still inconclusive.

    10 What are the other factors related to colorectal cancer?

    (1) Frequent radiation of the large intestine can cause colorectal cancer: When some gynecological cancers receive radiotherapy, a certain local intestinal tube also receives a lot of radiation, the tissue is damaged, and the cells mutate to become colorectal cancer.

    (2) Tumors in other parts of the body: If you have a history of cancer, it is also one of the risk factors for colorectal cancer. Cancers in other parts of the body can also cause colorectal cancer through certain transmission routes.

    (3) Malignant transformation of benign masses in the large intestine: Many clinical studies have proven that benign polyps in the large intestine can undergo malignant transformation and become colorectal cancer (such as hyperplastic polyps, inflammatory polyps, adenomas, etc.). The larger the larger, the higher the rate of malignant transformation. Relevant data show: colorectal polyps with a diameter of less than 1 cm have a cancer rate of about 5%; those with a diameter of 1-2 cm have a cancer rate of about 13%; those with a diameter of more than 2 cm have a cancer rate. The rate is as high as 41%. Therefore, everyone has reached a consensus that benign tumors of the large intestine are precancerous lesions. Colorectal cancer develops in accordance with the law of normal mucosa to polyps to cancer.

    (4) Long-term chronic constipation is closely related to colorectal cancer: due to long-term constipation, some toxins and carcinogens in the body cannot be excreted through the stool in time, so that these harmful substances can stimulate the intestinal mucosa for a long time in the large intestine, leading to chronic inflammation and Hyperplasia, eventually becoming cancer.

    (5) Some trace elements are related to colorectal cancer: Studies have shown that the soil in the high-incidence area of ​​colon cancer lacks trace elements selenium and molybdenum. Selenium supplementation can inhibit the occurrence of colorectal cancer, indicating that the content of certain trace elements is related to colorectal cancer. There is a direct relationship between the occurrence of and its specific mechanism is still under study. It is speculated that trace elements may act through enzymes.

    11 How is colorectal cancer hereditary?

    When it comes to inheritance, people often have such a misunderstanding, as if one parent has colorectal cancer, it will be passed on to the next generation, and children must also have colorectal cancer.In fact, colorectal cancer itself is not hereditary. Medically speaking, colorectal cancer has a certain heredity. It mainly refers to two autosomal dominant inherited diseases-familial multiple colorectal polyposis or familial adenomatous polyposis, and hereditary non- Polyposis colorectal cancer. Patients with familial adenomatous polyposis usually start to develop after puberty, manifesting as hundreds of thousands of growths in the large intestine and often multiple cancerous changes. Hereditary non-polyposis colorectal cancer often occurs in the right colon, manifested by the growth of multiple villous adenomas in the intestine, and the number is not as large as that of patients with familial hemoroma polyposis. The changes in molecular biology of these two chromosomal dominant genetic diseases are different. In patients with familial adenomatous polyposis, the gene on the fifth pair of chromosomes has a mutation, while hereditary non-polyposis colorectal cancer is mainly DNA Pairing errors repair gene mutations. As for sporadic colorectal cancer, although the proportion of family members suffering from colorectal cancer is higher than that of other people, it is currently believed that this is caused by the environment of living together. In other words, whether the colorectal cancer that we generally suffer from is hereditary, there is no clear scientific answer.

    12 Which chronic inflammation of the intestine can cause cancer?

    As we have mentioned in the relevant chapters, chronic ulcerative colitis is prone to cancer, which is characterized by the younger the age, the longer the course of the disease, the higher the cancer rate, which is about 5%, such as ulcerative colitis for 25 years. , The risk of cancer is 42%-45%. Crohn's disease can also become cancerous, but the risk of canceration is lower than that of ulcerative colitis. The canceration rate for people with a disease course of more than 20 years is about 2.8%. In addition, patients with intestinal schistosomiasis can cause tissues to become cancerous due to the deposition of schistosome eggs on the intestinal mucosa. Other intestinal inflammations such as bacillary dysentery and amoebic dysentery can become cancerous through granulomas. Therefore, various chronic inflammations of the intestine must be actively treated.

    13 Where do colorectal polyps come from?

    Colorectal polyps are tumors that grow on the mucosa of the large intestine. It is an abnormal new tissue that is inconsistent with the surrounding tissues. It is due to the effect of various stimulating factors on the colorectal mucosal cells (such as polycyclic hydrocarbons and heterocyclic amines that are decomposed from food in the intestine). Compounds, etc.), and once this abnormal hyperplasia occurs, even if the stimulus stops stimulating, the hyperplasia will continue, resulting in polyps. Those proliferating cells that are mature and grow slowly become benign tumors of the large intestine, while those that are immature and grow rapidly become malignant tumors of the large intestine.

    14 Are polyps of different natures cancerous the same?

    In histology, polyps are divided into neoplastic polyps and non-neoplastic polyps. Tumor polyps are divided into tubular adenomas, villous adenomas and villous tubular adenomas according to their tissue morphology. Someone has done an analysis of the factors of adenoma tissue type and carcinogenesis and found that different tissue types have different rates of canceration. The carcinogenesis rate of tubular adenoma is about 8.6%, the carcinogenesis rate of villous tubular adenoma is about 22%, and the carcinogenesis rate of villous adenoma is about 62.5%. In addition, studies have shown that the more serious the dysplasia of the glandular epithelium of polyps, the greater the risk of cancer. More than 80% of patients with colorectal adenoma over 50 years old will develop cancer. Whether non-neoplastic polyps such as inflammatory polyps become cancerous is still controversial. If you have a non-neoplastic polyp, it should be closely monitored and surgically removed if necessary.

    15 How many kinds of histology are there for colorectal cancer?

    When there is a tumor on the large intestine, the doctor will take a small piece of it and send it to the pathology department, and observe the histological structure under a microscope to confirm the diagnosis. In the histology, large intestine cancer often has the following types.

    (1) Adenocarcinoma: The vast majority of colorectal cancers are adenocarcinomas, because the large intestine is an organ with an adenoid structure. Under the microscope, cancer cells are arranged in irregular glandular tubes. According to the degree of differentiation of cancer cells can be divided into I-IV level.

    (2) Mucinous adenocarcinoma: Intestinal glands can secrete mucus. After tumors grow, intestinal adenocarcinomas often secrete large amounts of mucus, making the cancer cells appear as translucent capsules, so it is called mucinous adenocarcinoma. The nucleus is seen under the microscope. Squeezed to the side, like a ring, it is also called signet ring cell carcinoma, which is highly malignant.

    (3) Undifferentiated carcinoma, squamous cell carcinoma, and adenosquamous carcinoma: Undifferentiated carcinoma is very heterotypic in cell morphology, so it has the highest degree of malignancy and the worst prognosis; squamous cell carcinoma, adenosquamous carcinoma, etc. are intestinal tissues with squamous epithelium Caused by metaplasia. This type of bowel cancer is rare.

    16 How is colorectal adenocarcinoma staged?

    In order to better explain the degree of cancer development and formulate corresponding treatment strategies, malignant tumors are clinically staged. In 1978, the Hangzhou Colorectal Cancer Conference developed a modified Dukes staging trial plan.

    Stage I 0: The lesion is confined to the mucosal layer (including carcinoma in situ and focal carcinoma) and can be locally excised.

    Stage I 1: The lesion only invades the submucosa (early invasive carcinoma).

    Stage I 2: The lesion invades the muscle layer.

    Stage II: The lesion penetrates the intestinal wall or invades surrounding tissues and organs, but radical resection can still be done.

    Stage III 1: With metastasis to lymph nodes near the cancerous focus (lymph nodes near the wall of the intestine and the peripheral blood vessels).

    Dish stage 2: With lymph node metastasis around blood vessels and mesangial margin, but radical resection can be done.

    Stage IV 1: With distant organ metastasis.

    Stage IV 2: With distant lymph node metastasis or extensive metastasis of the lymph nodes at the root of the supply vessel, it cannot be completely removed (the anterior or para-aortic and internal iliac vascular lymph nodes, etc.).

    Stage IV 3: With extensive peritoneum spread, it cannot be completely removed.

    Stage IV 4: The lesion has extensively infiltrated adjacent organs and cannot be resected. Palliative resection can be performed if the general condition allows.

    17 What is the incidence of colorectal cancer?

    In terms of gender, there is almost no gender difference in the incidence of colon cancer, while the incidence of rectal cancer is higher in men than in women. Geographically speaking, developed Western Europe, North America and other countries have a higher incidence rate, reaching 25-35/100,000 population. The incidence rate in underdeveloped countries is relatively low. The incidence rate in developing countries such as Asia and Africa is about 0.6-5.0 persons per 100,000 population, which is significantly lower than that in Western countries.

    China is a developing country, and the incidence of colorectal cancer was lower than 10 people per 100,000 population in the middle of the last century. Twenty years ago, the incidence of colorectal cancer in China was ranked after lung, liver, and stomach cancer in men, and breast cancer, cervical cancer, lung cancer, and stomach cancer in women. In recent years, the incidence of colorectal cancer in China has increased year by year, reaching 24 people per 100,000 population by the beginning of this century. A recent study on the epidemiology of malignant tumors, which has just won the second prize of the National Science and Technology Progress Award in 2006, reveals that by 2010, the incidence of cancer in China is ranked among the top three. Men are lung cancer, liver cancer, and colorectal cancer, and women are breast. Cancer, lung cancer and colorectal cancer. The northeast, north and southeast coasts of China are areas with a high incidence of colorectal cancer. In addition, the incidence of colorectal cancer in China in recent years has also been characterized by a tendency to be younger, and the incidence of young and middle-aged people under 40 is higher than that in European and American countries.

    18 Which section of the intestine is the most common site for colorectal cancer? why?

    The entire large intestine is divided into the ascending colon (including the ileocecal area, transverse colon, descending colon, sigmoid colon, and rectum) from the ileocecal area on the right side to the left side to the rectum. Because benign masses such as intestinal polyps are precancerous lesions Therefore, the common site of colorectal polyps is also the common site of colorectal cancer. A large number of clinical observations have found that 50% of cancers occur in the rectum, and 25% occur in the sigmoid colon (mainly at the junction of straight and second), that is, 75% of cancers. Colorectal cancer is on the left side, followed by the ileocecal area on the right side. The reason for this is related to the function of the large intestine. The main function of the large intestine is to absorb the water in the food residue, make it gradually shape, become feces and be discharged . Food residues are gradually absorbed in the process of moving, and feces have been formed when they reach the sigmoid colon. At this time, harmful substances and carcinogens in the feces are also highly concentrated. If they cannot be excreted in time, some bacteria (such as anorexia) Under the action of aerobic bacteria), the intestinal mucosa will be adversely stimulated for a long time, causing the intestinal mucosa to undergo hyperemia, exudation, edema and other inflammatory reactions and be damaged. Some genes may occur in the process of repairing the damage of intestinal epithelial cells. Mutations, defects, and loss of normal functions result in dysplasia and tumor-like hyperplasia of the intestinal epithelium, which eventually become malignant and become colorectal cancer.

    19 What are the main clinical symptoms of colorectal cancer?

    The location of colorectal cancer in the large intestine is different, and the clinical symptoms are also different. Tumors that grow in the rectum are called rectal cancer. The most common symptoms of rectal cancer are: increased stool frequency, but not much or even a small amount of defecation per time; tenesmus and incomplete defecation, similar to dysentery, medically called rectal irritation. There is also blood in the stool, the blood is slightly dark red, and patients often think of hemorrhoid bleeding. As the disease progresses, the cancer will increase and the symptoms of rectal stenosis and obstruction will appear. Symptoms such as constipation, thinning of notes, abdominal distension and pain will appear.

    No matter where the tumor grows in the colon, it is called colon cancer. The most common symptom of colon cancer is blood in the stool. The stools of patients are often not formed and mixed with dirty dark red blood. When the tumor continues to grow, there will be abdominal pain, abdominal palpation and masses. The locations of abdominal pain and abdominal masses differ depending on where the tumor grows. Continuing to develop, there will be signs of cachexia such as intestinal obstruction, anemia, fever, and weight loss.

    In addition, it should be noted that rectal cancer infiltrates into the anal canal, and symptoms such as anal hardening and persistent anal pain will occur. This is also a symptom of anal cancer.

    To sum up, the most common and earliest symptoms of colorectal cancer are blood in the stool and loose stools. At this time, it is also the most misdiagnosed time. You must go to the anorectal department of the hospital for an examination to confirm the diagnosis.

    20 What are the common complications of colorectal cancer?

    There are three common complications of colorectal cancer.

    (1) Intestinal obstruction: Colorectal cancer usually occurs in the left large intestine. The left large intestine is anatomically narrower than the right colon, especially the sigmoid colon has the narrowest lumen and forms an acute angle with the rectum; in addition, tumors of the left large intestine Most of them are invasive cancers that can cause annular narrowing of the intestinal cavity. The above determines that the obstruction of colorectal cancer is mostly on the left side, which is a gradual obstruction. The patient gradually develops symptoms of more and more difficult defecation, and the abdominal pain gradually worsens, and nausea and vomiting may occur. Since the intestinal lumen of the right colon is relatively wide, and the stool in the right inverted large intestine is still liquid, and the right colorectal tumors are mostly mushroom-shaped, the right colorectal cancer is not prone to obstruction. If it causes intestinal obstruction, the tumor must be quite large .

    (2) Intestinal bleeding: This is the most common symptom of colorectal cancer, and it is often the main complaint of patients with colorectal cancer. The amount of bleeding can be large or small, dirty and dark, and need to be related to hemorrhoids, anal fissures, ulcerative colitis, etc. Distinguish the disease phase.

    (3) Intestinal perforation: Patients with colorectal cancer combined with intestinal perforation and peritonitis, manifested as persistent severe abdominal pain, high fever, nausea, vomiting, profuse sweating, oral cavity, abdominal tenderness and rebound pain. Urgent treatment is needed, and laparotomy is necessary if necessary.

    21 What are the advantages and disadvantages of the stool occult blood test?

    Fecal occult blood test is an inspection method that uses oxidation-reduction reaction to check the hemoglobin in the stool to infer whether there is bleeding in the intestine. The advantage of this method is that it is cheap, convenient and easy to make, patient-free, and easy to accept; the disadvantage is that the test is easily interfered by some foods and drugs, and false positive and false negative test results are prone to appear.

    There is also a method of checking fecal occult blood called immunoassay, which uses anti-heme antibody to check whether there is human heme in the stool, which has a high specificity.

    No matter which test method, the positive rate (reliability) is not 100%, so the stool occult blood test is suitable for preliminary screening. When the signs of colorectal cancer are obvious, this method is not necessary. This method is also not used when the eyes are bloody.

    22 What are the advantages and disadvantages of carcinoembryonic antigen test?

    Taking venous blood for carcinoembryonic antigen (CEA) examination is a method of detecting or monitoring cancer that has emerged in recent years. The large intestine is an organ with an adenoid structure. Colorectal cancer is an adenocarcinoma, that is, a malignant tumor that occurs in the glandular epithelium. When an adenocarcinoma occurs in the human body, the cancer cells will release a glycoprotein. We can use chemiluminescence from the serum This glycoprotein is detected in the carcinoembryonic antigen test.

    The advantages of testing CEA are simple and easy, no pain, moderate cost, and ordinary civilians can fully bear it. Its shortcoming or defect is that its specificity is not high, because our stomach, liver, pancreas, breast and other organs have adenoid structures rather than unique to the large intestine. In addition, CEA can also be elevated in some normal people, such as The serum CEA of smokers is higher than that of non-smokers, so when the CEA of the test is elevated, it does not mean that you have colorectal cancer. However, this test is very meaningful as a cancer screening and monitoring of recurrence after colorectal cancer treatment.

    23 What are the advantages and disadvantages of barium enema examination for colorectal cancer?

    Barium enema is one of the important methods to check colorectal tumors. Before the examination, fasting, clean the intestines, and then irrigate the large intestine with high-concentration, low-viscosity, fine-grained barium, and track the movement of the barium in the large intestine under X-ray fluoroscopy to see if there is any stenosis, Abnormalities such as expansion, unevenness and filling defect. Its advantages are less pain, relatively low cost, and a clearer observation of the mucosal structure in the intestinal cavity and the surface of the intestinal wall; the disadvantage is that the preparation stage is troublesome, and the radiation is irradiated for about 20 minutes for a long time to correct, which will cause certain damage to the body. For early cancer, when the x-ray signs are not obvious, the diagnosis may be missed, and it is still unable to observe the conditions inside and outside the intestinal wall, etc. Therefore, barium enema examinations are generally rarely done except in special cases. .

    24 What are the advantages and disadvantages of colorectal CT and magnetic resonance examination?

    CT is the abbreviation for computerized tomography. The advantage of CT is that it can clearly show the conditions of the intestinal cavity, in the intestinal wall, outside the intestinal wall, and adjacent tissues and organs, so it can determine the shape of the tumor in the intestinal cavity, the degree and extent of involvement of the intestinal wall and adjacent tissues and organs outside the intestine, etc. See it clearly. The disadvantage of CT is the poor resolution of soft tissues, and sometimes it is necessary to inject contrast agents, so there is a certain risk, and X-rays also have certain damage to the human body.

    The principle of magnetic resonance (MRI) examination is as follows: there are a large number of hydrogen nuclei in human tissues and organs, which we call protons. Protons have the properties of spin and magnetic moment. Under the action of a magnetic field, the protons rotate around the direction of the magnetic field. , When the proton spin frequency is the same as the frequency of the magnetic field, resonance occurs, which is called magnetic resonance. Because the density of various tissues and organs of the human body is different (called proton density), the time required for resonance of different proton densities is very different. The computer can process these differences and convert them into images. This is a magnetic resonance examination.

    The advantages of CT resonance examination are: First, there is no damage to the body caused by ionizing radiation. Second, unlike CT, artifacts can appear, so the image quality is good. Third, the resolution of soft tissue is higher than that of CT. The disadvantages of MRI are: First, it is expensive. Second, the spatial resolution is poor. Third, people with metal foreign bodies (such as pacemakers) cannot be checked.

    25 What are the advantages and disadvantages of colonoscopy?

    There are three types of colonoscopy: proctoscope, sigmoidoscopy and fiber colonoscopy. No matter which type of colonoscopy, the intestinal tract can be clearly observed intuitively, and the theoretical diagnosis rate is 100%.

    The rectal mirror is made of metal, is straight and 15 cm long. Proctoscopy does not require bowel preparation, is basically painless, easy to operate, and low in cost. It is very suitable for rectal cancer screening; the disadvantage is that it is limited to rectal examination.

    The sigmoidoscopy is also a straight tube, 25-30 cm long. Since most bowel cancers occur in the intestine within 30 cm from the anus, the advantages of sigmoidoscopy are also obvious, that is, low cost and less pain, but it is impossible to detect tumors above the descending colon.

    Fiber-optic colonoscopy can perform visual inspection of the entire large intestine; the disadvantages are troublesome preparations, high cost, and painful pain. One-third of patients give up halfway due to poor tolerance, and patients with severe cardiovascular diseases cannot Do this check.

    26 How to selectively check for colorectal cancer?

    Many methods of detecting colorectal cancer each have their advantages and disadvantages. When intestinal cancer is suspected, there is no need to check them one by one. You can do some of them selectively according to your own situation.

    If there are changes in stool characteristics, blood in the stool, especially dark blood, symptoms of anemia, weight loss, and abdominal discomfort, especially when a lump can be felt in the abdomen, a colorectal cancer examination should be performed.

    (1) The basic steps of a doctor's examination are as follows:

    1) Learn more about the medical history.

    2) Physical examination and digital anal examination.

    3) If the lower rectal disease is excluded by the digital anal examination, and the patient's physical condition allows, he can directly prepare for fiber colonoscopy, and those with poor health can have a sigmoidoscopy first.

    4) When it is necessary to take venous blood to test certain items, the carcinoembryonic antigen test can be added.

    5) When colonoscopy is found to have tumors, biopsy should be taken for pathological examination. CT or MRI can also be done to further understand the degree of tumor invasion of surrounding tissues and organs.

    (2) Routine physical examination: If we only have a physical examination to check for colorectal cancer, then we only need to perform a digital anal examination, check the stool occult blood (preferably 3 times in a row) and carcinoembryonic antigen. Those with conditions should also do a sigmoidoscopy. Routine physical examination is best performed once a year.

    (3) Postoperative colorectal cancer: In order to monitor whether there is recurrence, carcinoembryonic antigen should be reviewed every quarter for 3 years after surgery, and carcinoembryonic antigen should be reviewed every six months for 5 years after the operation. Carcinoembryonic antigen is rechecked once, and colonoscopy is checked once a year for those who are eligible.

    27 How does colorectal cancer look under endoscopy?

    The morphology of colorectal cancer seen under endoscopy can be roughly divided into the following types, which are often referred to as microscopic types.

    (1) Ulcer type: The most common type, which usually occurs in the left colon and rectum. It is raised all around and sunken in the middle, like a volcanic crater, with septic blood and dirty secretions visible on the ulcer surface.

    (2) Hyperplastic type: mostly cauliflower-like hyperplasia, the tumor protrudes into the large intestine cavity, the surface is not smooth, the texture is brittle, the touch is bleeding, the blood is dark, and the erosion surface and necrosis can be seen on the tumor.

    (3) Infiltrating type: This type occurs in the left colon, especially at the junction of the rectum and the sigmoid colon and the rectum. The tumor tissue infiltrates and grows along the intestinal wall, and there is extensive connective tissue hyperplasia. Under the microscope, the lesion is narrow or even narrow, the intestinal wall becomes hard, loses its softness and elasticity, and can easily cause intestinal obstruction.

    (4) Lump type: It occurs in the right colon and ileocecal area. The mass is spherical or hemispherical and grows into the intestinal cavity, with ulcers on the surface and easy bleeding. This type is less invasive and less metastatic, and generally has a good prognosis.

    28 What diseases should colorectal cancer be differentiated from?

    Colorectal cancer includes colon cancer and rectal cancer. Colon cancer should be distinguished from ulcerative colitis, Crohn’s disease, intestinal tuberculosis, schistosomiasis granuloma, amoebic granuloma, etc. Rectal cancer should be mainly related to hemorrhoids, bacillary dysentery, amoebic dysentery, schistosomiasis, etc. Identify.

    (1) Ulcerative colitis: Ulcerative colitis is referred to as ulcerative colitis, which has been described in related chapters. Its main characteristic manifestations are abdominal pain, diarrhea, mucus, pus and blood in the stool. It can be distinguished from colon cancer and rectal cancer by doing sigmoidoscopy or fiber colonoscopy.

    (2) Crohn's disease: Almost all Crohn's disease are initially misdiagnosed as appendicitis. The main symptoms of Crohn's disease are abdominal pain, diarrhea, fever and abdominal masses. Fiber colonoscopy is the best means of identification. The main manifestations of Crohn's disease under microscope are large and deep fissure ulcers, pebble sign, and segmental intestinal panmural inflammation.

    (3) Intestinal tuberculosis: Intestinal tuberculosis is mainly manifested as symptoms of systemic poisoning of tuberculosis such as abdominal pain, loose stools, abdominal mass, low fever, and night sweats. There are also proliferative tuberculosis in constipation. Most patients with intestinal tuberculosis come from pulmonary tuberculosis. The patients with intestinal tuberculosis are mostly positive through the erythrocyte sedimentation rate, tuberculin test, and X-ray barium contrast examination, which is not difficult to distinguish from colorectal cancer.

    (4) Schistosomiasis and its granuloma: Patients with life history in Jiangnan should pay attention to the identification of schistosomiasis. The intestinal lesions of schistosomiasis are mainly left colon, with abdominal pain, diarrhea and blood in the stool as the main symptoms; colonoscopy can be used to identify the granuloma, and a biopsy of the granuloma must be taken.

    (5) Amoebic dysentery and its granuloma: Amoebic is a human intestinal parasite, which lives in the wall of the large intestine by ingesting intestinal mucosa fragments and red blood cells, causing amoebic dysentery. The symptoms are similar to those of colorectal cancer, but the stool is smelly and jam-like. Amoebic trophozoites or cysts can be found in the stool for identification. Colonoscopy can take tissue biopsy of the granuloma, which can also be identified.

    (6) Hemorrhoids: Blood in the stool is the main symptom of bowel cancer and hemorrhoids, especially in the early stages of the two, which can be the only symptom of each. Therefore, there are many cases where bowel cancer is misdiagnosed as hemorrhoids. Although both have blood in the stool, there are still differences between them. The color of hemorrhoids is bright red, blood and stool are not mixed (that is, blood is blood, it is stool); cancer bleeding, the color is dark red, blood and stool are mixed . Through digital examination and colonoscopy, it is easy to distinguish the two.

    (7) Chronic bacillary dysentery: The main symptoms of chronic bacillary dysentery are left lower abdominal pain, diarrhea, tenesmus, mucus pus and blood in the stool, which are quite similar to intestinal cancer. Those who are over 40 years old must pay attention to these symptoms and consult a specialist. Do digital anus examination and stool bacterial culture for identification. Those who are positive for Shigella dysentery cultured are chronic bacillary dysentery. Otherwise, further examinations should be done to avoid missed diagnosis of bowel cancer.

    29 Why is colorectal cancer easy to be misdiagnosed?

    According to statistics, the misdiagnosis rate of colon cancer is 40%, and the misdiagnosis rate of rectal cancer is 60%-70%. So why is colorectal cancer so easy to be misdiagnosed? According to the author’s experience, the reasons for the misdiagnosis can be summarized as follows.

    (1) Patients do not pay enough attention to their ideology and have fluke psychology: Many male patients do not care about minor illnesses and think that they are in good health; resistance to first resistance will pass, and they have a manhood attitude and a fluke mentality. The so-called serious illness will not come to oneself, and the result will be catastrophe, and it will be too late to regret.

    (2) Shy mentality: Many women fall into this category. When they see the doctor is a man, they turn around and leave, or find a doctor without examination and blindly treat themselves and eventually harm themselves.

    (3) It is considered that the old disease has relapsed and delayed the condition: Many patients who have had hemorrhoids or chronic enteritis in the past belong to this category. Since the disease has been repeated for more than ten years, I have been ill for a long time and the doctor knows what medicine to use, so that he relaxes his vigilance and does not have a regular review. Only when he is cured for a long time or the condition is getting worse, the checkup is already advanced. The author has encountered many cases, and I am very sorry for them.

    (4) The condition is complicated and the clinical symptoms are atypical: the large intestine is about 1.3-1.5 meters long, and tumors can grow in any part of the large intestine. Due to the different growth positions of the tumors, the clinical symptoms are very different, especially the tumors longer than the ileocecal area, ascending colon and transverse colon. Swelling, early symptoms are not typical or even no obvious symptoms, almost all of them are mistaken for "tired", "cold", "dietary discomfort", "chronic appendicitis", etc. and miss the best opportunity for surgery. For cancers that grow in the descending colon, sigmoid colon and rectum, abdominal pain, bloating, constipation, and blood in the stool are common symptoms, and they are often misdiagnosed as "habitual constipation", "hemorrhoids" and other diseases.

    The only way to reduce the misdiagnosis rate is to "pay attention." For every clinical symptom, if there is no obvious effect after 3-5 days of treatment, you must go to a national regular hospital for examination.

    30 What are the ways of metastasis of colorectal cancer?

    Colorectal cancer has three main ways of metastasis or three methods of transmission.

    (1) Direct spread: The cancer tissue infiltrates from the intestinal mucosa to the submucosa and muscle layer until it spreads to adjacent tissues and organs, such as the bladder, uterus, and mesenteric.

    (2) Lymphatic metastasis: The lymphatic metastasis of rectal cancer is more complicated, and it can metastasize upward, downward, or to both sides. The most common site of upward metastasis is the lymph nodes adjacent to the superior rectal artery, which can be metastasized to the anal sphincter and perianal skin, and to the internal iliac vascular lymph nodes and lateral ligament lymph nodes on both sides, but most rectal cancers still metastasize upwards. Colon cancer can spread to the lymph nodes next to the colon, around the mesenteric vessels, and the roots of the mesenteric through lymph. Advanced colon cancer can metastasize to the inguinal lymph nodes and supraclavicular lymph nodes.

    (3) Blood dissemination: After colorectal cancer invades the local venules, the tumor thrombus can be transferred to the liver through the portal vein with venous blood, causing secondary liver cancer, which is the most distant metastasis site of colorectal cancer; followed by the lungs of colorectal cancer Metastasis; bowel cancer can also metastasize to the kidney and adrenal glands, brain, bone, skin, etc.

    In addition, cancer cells shed by colorectal cancer fall on the omentum, abdominal cavity or internal organs, which can cause so-called "planting metastasis". This transfer method is generally attributed to direct spread.

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