Introduction to colorectal cancer (CRC)

Introduction of colorectal cancer (carcinoma of colon and rectum) common malignant tumors in the gastrointestinal tract, early symptoms are not obvious, with the increase of cancer, manifestations of changes in bowel habits, blood in the stool, diarrhea, alternating diarrhea and constipation, local abdominal pain and other symptoms In the late stage, it shows systemic symptoms such as anemia and weight loss. Its incidence and mortality are second only to gastric cancer, esophageal cancer and primary liver cancer in digestive system malignancies. Overview Colorectal cancer is a common malignant tumor in the gastrointestinal tract. The early symptoms are not obvious. As the cancer increases, it shows changes in bowel habits, blood in the stool, diarrhea, alternating diarrhea and constipation, and local abdominal pain. In the advanced stage, it shows systemic symptoms such as anemia and weight loss. Its incidence and mortality are second only to gastric cancer, esophageal cancer and primary liver cancer in digestive system malignancies. China is a low-incidence region in the world, but its incidence has increased in varying degrees in many regions. Men with more than a middle-aged disease are most common in the 40-70 age group, but it is not uncommon to find those under 30 years old at the end of the 20th century. The ratio of male to female sex is about 2:1. The disease is the same as other malignant tumors. The cause of the disease is still unclear. It can occur in any part of the colon or rectum, but it is most common in the rectum and sigmoid colon. The rest are found in the cecum, ascending colon, descending colon and transverse colon. Most of the cancers are adenocarcinomas, and a few are squamous cell carcinomas and mucinous carcinomas. The disease can be spread to other tissues and organs through lymphatic, blood circulation and direct spread. According to clinical manifestations, X-ray barium enema or fiberoptic colonoscopy, the diagnosis can be confirmed. The key to treatment is early detection, timely diagnosis and radical surgery. The prognosis of this disease depends on early diagnosis and timely surgical treatment. Generally, the cancer is limited to the intestinal wall, and the prognosis is poor. The prognosis of the invasive to the intestine is poor. The prognosis of young patients, cancer infiltrates, metastasis or complications is poor. The cause is not well understood, but it is known to be related to the following precancerous lesions and some factors: 1 In many clinical practice, colon polyps can be malignant, with papillary adenomas most susceptible to malignancy, up to 40%; in familial polyps Among patients with disease, the incidence of cancer is higher, indicating that colon cancer is closely related to colon polyps. 2 parts of chronic ulcerative colitis can be complicated by colon cancer, the incidence may be 5 to 10 times higher than the normal population. The cause of colon cancer may be related to the chronic inflammatory stimuli of the colonic mucosa. It is generally believed that during the process of inflammatory hyperplasia, cancer occurs through the inflammatory polyp stage. 3 In China, schistosomiasis complicated with colon cancer is not uncommon, but there is still debate about its causal relationship. 4 According to the World Cancer Epidemiological Survey, the incidence of colon cancer in North America, Western Europe, Australia, New Zealand and other places is high, but lower in Japan, Finland, Chile and other places. According to the study, this geographical distribution is related to the dietary habits of residents, and the incidence of high-fat diet is higher. 5 The incidence of colon cancer may be related to genetic factors, which has been paid more and more attention. Pathological ulcer type colorectal cancer occurs in the left colon, the cancer is small, and early depression forms a depression, which easily causes bleeding and penetrates the intestinal wall to invade adjacent organs and tissues. Clinical manifestations of bloody stools are the main symptoms of colon cancer, and are the first and most common symptoms of rectal cancer. The amount of bleeding and traits vary depending on where the cancer is located. Patients with polypoid colorectal cancer may have localized abdominal pain and diarrhea in the lower right abdomen. The stool is sparsely watery, pus-like or jam-like, and the fecal occult blood test is mostly positive. As the cancer grows, a lump can be felt in the corresponding part of the abdomen. Stenotic colorectal cancer is prone to intestinal obstruction, alternating abdominal pain, bloating, diarrhea or diarrhea and constipation. Feces are pus or bloody stools. Patients with ulcerative colorectal cancer may have abdominal pain, diarrhea, blood in the stool or pus and bloody stools, and may cause intestinal stenosis and obstruction. Once complete obstruction occurs, abdominal pain is aggravated, and abdominal distension, nausea, vomiting may occur, and the systemic condition changes drastically. . In the late stage of the tumor. Sustained small amount of blood in the stool can cause anemia; long-term anemia, malnutrition and local ulceration, poisoning symptoms caused by absorption of toxins, leading to patients with weight loss, mental dysfunction, general weakness and cachexia; acute peritonitis can be caused by acute perforation Liver enlargement, ascites, neck and supraclavicular lymph nodes, often suggesting advanced tumor metastasis. Diagnosis of this disease should be done early diagnosis. For patients with recent changes in bowel habits or bloody stools, the rectal examination, X-ray barium enema, sigmoidoscopy or fiberoptic colonoscopy should be performed without loss of opportunity. X-ray tincture air double contrast angiography can show signs of sputum filling defect, intestinal stenosis, mucosal destruction, etc., to determine the location and extent of the tumor. Sigmoidoscopy and fiberoptic colonoscopy can directly observe the morphology of the whole colon and rectal mucosa. It can be used for biopsy of suspicious lesions under direct vision, which is valuable for improving the accuracy of diagnosis, especially for the early diagnosis of small lesions. Rectal examination is the simplest and most important method for the diagnosis of rectal cancer. It can not only find the mass, but also determine the location, size, shape, surgical procedure and prognosis of the tumor. Many patients with rectal cancer often do not have it. Timely doing this examination was misdiagnosed as sputum, enteritis, etc., resulting in long-term delay in treatment. Fecal occult blood test is a simple and easy method for early diagnosis of early diagnosis. Although it has no specificity, it can treat patients with persistent, repeated occult blood positive and no cause to be found. It is often alert to the possibility of colon cancer, especially to the right half. Colon cancer is more important. Carcinoembryonic antigen (CEA) is considered to be associated with malignant tumors, but it is not specific for colorectal cancer. It can be used as an adjunct to diagnosis. As the cancer CEA gradually declines after cancer resection, it will increase again when there is recurrence, so it can It is used to judge the prognosis of the disease or whether there is recurrence. Right colon cancer showing symptoms such as diarrhea, positive fecal occult blood test, and right abdomen mass should be distinguished from intestinal tuberculosis, localized colitis, schistosomiasis, amebiasis, etc.; manifested as abdominal pain, diarrhea and Left colon cancer with symptoms such as constipation alternation, bloody stool or pus and bloody stool should be distinguished from diseases such as convulsions, dysentery, ulcerative colitis, and colon polyps. The radical treatment of surgical treatment of intestinal cancer has so far been the first surgical treatment. The 1st National Intestinal Cancer Conference proposed that the radical resection of invasive intestinal cancer is defined as a radical resection of the tumor seen in the eye, including the primary lesion and the lymph node in the drainage area. Resection of the lesion, but the residual of the naked eye or the tumor is a palliative operation. Therefore, the lesions should be limited to the primary or regional lymph nodes should be radical surgery; local lesions are extensive, it is estimated that it is not easy to completely remove, but there is no distant metastasis can be used for palliative resection; local lesions can be removed more widely, but There is a distant metastasis, in order to relieve obstruction, improve symptoms can also be palliative resection; local lesions are extensive, adhesion, fixation, can not be removed, can be used for shortcut surgery or rash to relieve symptoms; there are distant metastasis such as liver metastasis Or other visceral metastases, but the original lesion can still be resected according to the specific circumstances of the patient to consider whether to remove at the same time, of course, this is also a palliative operation. Postoperative syndrome: Straight and colon cancer often have intestinal motility disorders after surgery, and the frequency of bowel movements increases; constipation is often caused by the destruction of colonic coordinated solid transport function after sigmoid colon resection; often after anal canal and colon anastomosis Changes in bowel function, such as increased frequency of bowel movements, incontinence, etc. Rectal cancer often has urinary dysfunction and sexual dysfunction after surgery. For patients with non-reserved anus, the "artificial anus" placed in the perineum is being studied and designed, and the device for controlling the stool can be used to solve the patient's defecation problem. The muscle excitatory technique of applying muscle instead of the sphincter is currently a promising approach. Radiation therapy In the past 50 years, despite the rapid development of surgical techniques, the surgical cure rate and 5-year survival rate of colorectal cancer have been hovering around 50%. The main reason for the failure of treatment is the high local recurrence rate, so the therapeutic effect of colorectal cancer is improved. Comprehensive treatment must be considered. At present, there are many studies and better results in the comprehensive treatment of surgery and radiation, including preoperative radiation, intraoperative radiation, postoperative radiation, "sandwich" radiotherapy, etc., and various comprehensive treatments have different characteristics. For advanced rectal cancer, especially local tumor infiltration into nearby tissues (pre-rectal, pre-rectal, abdominal lymph nodes, bladder, urethra, pubic symphysis) and patients with surgical contraindications, palliative radiation is often used with satisfactory results. Radiotherapy and surgical treatment 1, preoperative radiation (1) improve surgical resection rate (2) reduce lymph node involvement rate and percentage of advanced patients (3) reduce distant metastasis. (4) reduce the local recurrence rate and improve the survival rate 2, postoperative radiation (1) reduce the local recurrence rate: patients with early postoperative radiation, the effect will be better. (2) Improve survival rate: The 5-year survival rate of postoperative radiotherapy patients is significantly higher than that of surgery alone. (3) "sandwich" type radiotherapy In order to give full play to the advantages of preoperative radiation and postoperative radiation, and to overcome the shortcomings of both, the preoperative radiation-surgery-postoperative radiological method is called "sandwich" method. Read more...