Colorectal cancer, including colon and rectal cancer, is a common malignant tumor in China. In recent years, due to the influence of diet and environmental factors, the incidence of colorectal cancer is increasing year by year, ranking 4th among all kinds of malignant tumors, and its 5-year survival rate is between 25-50%, which seriously affects people’s life. Therefore, how to take corresponding preventive and screening measures to reduce the incidence of colorectal cancer, improve the early diagnosis rate and prolong the 5-year survival rate is the task and goal of medical workers, and is also an issue of great concern to the people.
I. What are the manifestations of colorectal cancer?
Early clinical symptoms of colorectal cancer can be asymptomatic or non-specific in early stage, so it is not valued by patients and doctors, but the stool occult blood test is mostly positive in early stage. In the later stage, the main symptoms are change of bowel habit, constipation or diarrhea, or alternation of constipation and diarrhea, increase of stool frequency, blood in stool, mucus stool, abdominal pain and distension, intestinal obstruction and other gastrointestinal symptoms and systemic symptoms such as anemia, fatigue, fatigue and fever.
Blood in stool is a common symptom of colorectal cancer, but it is not unique to it. Blood in stool may come from diseases in the digestive tract, such as hemorrhoids, anal fissure, rectal colon polyps, enteritis, etc., or it may be a manifestation of systemic diseases in the digestive tract.
How to distinguish blood in stool?
Generally, if the stool is tarry or blackish red, the bleeding site is mostly in the upper gastrointestinal tract. If the blood is red in color, it is mostly bleeding from lower GI tract diseases. Hemorrhoids and anal fissures have bright red blood in the stool, and the blood does not mix with the stool, and the amount can be large or small, or even jet-like bleeding. Colon cancer blood in stool is mostly purple or dark, often mixed with stool, accompanied by mucus stool, rectal cancer blood in stool is most similar to hemorrhoids, blood in stool is bright red or purple, attached to the surface of the stool, accompanied by mucus stool, may be accompanied by changes in stool properties, increased frequency of stool, alternating constipation and diarrhea, etc. Blood in the stool caused by rectal polyps is not easy to distinguish from colorectal cancer, so colonoscopy is required. Blood in the stool caused by ulcerative colitis, dysentery, etc. is mostly mixed with mucus or pus, accompanied by abdominal pain, fever, urgency, etc. In systemic diseases such as leukemia and hemophilia, blood in stool is only a part of systemic bleeding, and blood in stool will be accompanied by bleeding from other parts of the body.
The purpose of colorectal cancer screening is to detect, diagnose and treat early, study the natural development history of the disease, and find people at high risk so that they are in treatable stage and pre-cancerous state.
Who are the high-risk group and the general risk group?
U.S. guidelines: High-risk groups include those with family and personal history of colorectal cancer and adenoma, personal history of inflammatory bowel disease, and family history of adenomatous syndrome (including familial adenomatosis and hereditary nonpolyposis colorectal cancer) from the group. High-risk groups.
1, previous history of colorectal cancer and colorectal adenoma.
2. first-degree relatives with a history of colorectal cancer aged ≥ age of colorectal cancer patients – 10 years.
3. family members with hereditary non-polyposis colorectal cancer, age ≥ 10 years.
4, first-degree relative with a family history of adenoma, age ≥ 10
5, cholecystectomy for 10 or more years.
6, history of lower abdominal radiation for more than 10 years
7, a history of chronic schistosomiasis.
8, with two or more of the following.
(1) chronic diarrhea.
(2) mucus and blood stools.
(3) chronic constipation.
(4) chronic appendicitis.
(5) History of mental irritation.
(6) History of biliary tract disease.
What are the methods of colorectal cancer screening?
The following methods are commonly used.
1. Stool OB
Most commonly used, simple and easy, suitable for mass screening, can reduce the mortality rate of colorectal cancer by 15-33%, meat has influence, poor sensitivity and specificity, can be used as primary screening method.
2.Colonoscopy
It can observe the whole colon, biopsy and polyp treatment, and is the gold standard for diagnosis of colorectal cancer, but the intestinal preparation is complicated, with certain pain and danger, and high cost, and can be used as a re-screening method when other methods are positive.
3.Double contrast air-barium enema method
It is easy to miss the diagnosis of small lesions, cannot be treated, has poor sensitivity, and is not preferred for primary screening.
4.Simulated colonoscopy (CT colon imaging), sensitivity up to 90-98%, relatively poor for less than 6mm, expensive to intestinal preparation, only as a re-screening method for patients who are not willing to colonoscopy.
5.Capsule colonoscopy
It is painless, non-invasive, requires intestinal preparation, expensive, the whole colon picture is not fully satisfactory, cannot be biopsied and treated, and can only be used as a supplement for reluctant colonoscopists.
V. How to prevent colorectal cancer?
The main points are as follows.
1.Change dietary habits: control high protein and high fat foods, eat more fiber-rich foods, and eat less fried, baked, smoked and pickled foods. High protein and high fat foods can easily stimulate the secretion of bile, and the metabolites of bile acids are highly carcinogenic, which can easily cause colorectal cancer. High fiber not only helps to promote the excretion of carcinogenic substances in the intestine, but also dilutes the concentration of carcinogenic substances in the intestinal lumen. Smoked and pickled foods contain a large amount of nitrite and nitrosamines, and nitrosamines are the strongest carcinogenic substances that cause colorectal cancer to occur. Carcinogenic substances are also found in fried and baked foods, and it has been experimentally proved that methyl aromatic amine formed after high temperature pyrolysis of protein can induce colorectal cancer.
2.Actively treat inflammatory diseases of the large intestine. Intestinal bacteria, especially anaerobic bacteria, play an extremely important role in the occurrence of colorectal cancer. Chronic ulcerative colitis is also a relatively certain precancerous lesion, which generally increases by 10%-20% every 10 years after the onset of 10 years of cancer.
3, early removal of colorectal polyp-like lesions. Colorectal polyp-like lesions, including colorectal adenomas, are benign lesions most closely related to colorectal cancer.
4.Regular physical examination.